| Message ID | 20230413180622.1014016-1-15330273260@189.cn (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] drm/fbdev-generic: prohibit potential out-of-bounds access | expand |
Hi,
thanks for the patch. This is effectively a revert of commit
8fbc9af55de0 ("drm/fbdev-generic: Set screen size to size of GEM
buffer"). Please add a Fixes tag.
Am 13.04.23 um 20:06 schrieb Sui Jingfeng:
> From: Sui Jingfeng <suijingfeng@loongson.cn>
>
> The crazy fbdev test of IGT may write after EOF, which lead to out-of-bound
Please drop 'crazy'. :)
> access for the drm drivers using fbdev-generic. For example, run fbdev test
> on a x86-64+ast2400 platform with 1680x1050 resolution will cause the linux
> kernel hang with following call trace:
>
> Oops: 0000 [#1] PREEMPT SMP PTI
> [IGT] fbdev: starting subtest eof
> Workqueue: events drm_fb_helper_damage_work [drm_kms_helper]
> [IGT] fbdev: starting subtest nullptr
>
> RIP: 0010:memcpy_erms+0xa/0x20
> RSP: 0018:ffffa17d40167d98 EFLAGS: 00010246
> RAX: ffffa17d4eb7fa80 RBX: ffffa17d40e0aa80 RCX: 00000000000014c0
> RDX: 0000000000001a40 RSI: ffffa17d40e0b000 RDI: ffffa17d4eb80000
> RBP: ffffa17d40167e20 R08: 0000000000000000 R09: ffff89522ecff8c0
> R10: ffffa17d4e4c5000 R11: 0000000000000000 R12: ffffa17d4eb7fa80
> R13: 0000000000001a40 R14: 000000000000041a R15: ffffa17d40167e30
> FS: 0000000000000000(0000) GS:ffff895257380000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: ffffa17d40e0b000 CR3: 00000001eaeca006 CR4: 00000000001706e0
> Call Trace:
> <TASK>
> ? drm_fbdev_generic_helper_fb_dirty+0x207/0x330 [drm_kms_helper]
> drm_fb_helper_damage_work+0x8f/0x170 [drm_kms_helper]
> process_one_work+0x21f/0x430
> worker_thread+0x4e/0x3c0
> ? __pfx_worker_thread+0x10/0x10
> kthread+0xf4/0x120
> ? __pfx_kthread+0x10/0x10
> ret_from_fork+0x2c/0x50
> </TASK>
> CR2: ffffa17d40e0b000
> ---[ end trace 0000000000000000 ]---
>
> The indirect reason is drm_fb_helper_memory_range_to_clip() generate damage
> rectangles which partially or completely go out of the active display area.
> The second of argument 'off' is passing from the user-space, this will lead
> to the out-of-bound if it is large than (fb_height + 1) * fb_pitches; while
> DIV_ROUND_UP() may also controbute to error by 1.
>
> This patch will add code to restrict the damage rect computed go beyond of
> the last line of the framebuffer.
>
> Signed-off-by: Sui Jingfeng <suijingfeng@loongson.cn>
> ---
> drivers/gpu/drm/drm_fb_helper.c | 16 ++++++++++++----
> drivers/gpu/drm/drm_fbdev_generic.c | 2 +-
> 2 files changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index 64458982be40..6bb1b8b27d7a 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -641,19 +641,27 @@ static void drm_fb_helper_damage(struct drm_fb_helper *helper, u32 x, u32 y,
> static void drm_fb_helper_memory_range_to_clip(struct fb_info *info, off_t off, size_t len,
> struct drm_rect *clip)
> {
> + u32 line_length = info->fix.line_length;
> + u32 fb_height = info->var.yres;
> off_t end = off + len;
> u32 x1 = 0;
> - u32 y1 = off / info->fix.line_length;
> + u32 y1 = off / line_length;
> u32 x2 = info->var.xres;
> - u32 y2 = DIV_ROUND_UP(end, info->fix.line_length);
> + u32 y2 = DIV_ROUND_UP(end, line_length);
> +
> + /* Don't allow any of them beyond the bottom bound of display area */
> + if (y1 > fb_height)
> + y1 = fb_height;
> + if (y2 > fb_height)
> + y2 = fb_height;
>
> if ((y2 - y1) == 1) {
> /*
> * We've only written to a single scanline. Try to reduce
> * the number of horizontal pixels that need an update.
> */
> - off_t bit_off = (off % info->fix.line_length) * 8;
> - off_t bit_end = (end % info->fix.line_length) * 8;
> + off_t bit_off = (off % line_length) * 8;
> + off_t bit_end = (end % line_length) * 8;
Please scratch all these changes. The current code should work as
intended. Only the generic fbdev emulation uses this code and it should
really be moved there at some point.
>
> x1 = bit_off / info->var.bits_per_pixel;
> x2 = DIV_ROUND_UP(bit_end, info->var.bits_per_pixel);
> diff --git a/drivers/gpu/drm/drm_fbdev_generic.c b/drivers/gpu/drm/drm_fbdev_generic.c
> index 8e5148bf40bb..b057cfbba938 100644
> --- a/drivers/gpu/drm/drm_fbdev_generic.c
> +++ b/drivers/gpu/drm/drm_fbdev_generic.c
> @@ -94,7 +94,7 @@ static int drm_fbdev_generic_helper_fb_probe(struct drm_fb_helper *fb_helper,
> fb_helper->buffer = buffer;
> fb_helper->fb = buffer->fb;
>
> - screen_size = buffer->gem->size;
> + screen_size = sizes->surface_height * buffer->fb->pitches[0];
I guess we simply go back to this line. I'd R-b a patch that does
exactly this.
But some explanation is in order. Maybe you can add this as a comment to
the computation, as it's not obvious:
The value of screen_size should actually be the size of the gem buffer.
In a physical framebuffer (i.e., video memory), the size would be a
multiple of the page size, but not necessarily a multiple of the screen
resolution. There are also pan fbdev's operations, and we could possibly
use DRM buffers that are not multiples of the screen width. But the
update code requires the use of drm_framebuffer_funcs.dirty, which takes
a clipping rectangle and therefore doesn't work well with these odd
values for screen_size.
Best regards
Thomas
> screen_buffer = vzalloc(screen_size);
> if (!screen_buffer) {
> ret = -ENOMEM;
Hi, On 2023/4/14 03:16, Thomas Zimmermann wrote: > Hi, > > thanks for the patch. This is effectively a revert of commit > 8fbc9af55de0 ("drm/fbdev-generic: Set screen size to size of GEM > buffer"). Please add a Fixes tag. > > Am 13.04.23 um 20:06 schrieb Sui Jingfeng: >> From: Sui Jingfeng <suijingfeng@loongson.cn> >> >> The crazy fbdev test of IGT may write after EOF, which lead to >> out-of-bound > > Please drop 'crazy'. :) This is OK. By using the world 'crazy', I meant that the test is very good and maybe it is written by professional peoples with the guidance by experienced engineer. So that even the corner get tested. > >> access for the drm drivers using fbdev-generic. For example, run >> fbdev test >> on a x86-64+ast2400 platform with 1680x1050 resolution will cause the >> linux >> kernel hang with following call trace: >> >> Oops: 0000 [#1] PREEMPT SMP PTI >> [IGT] fbdev: starting subtest eof >> Workqueue: events drm_fb_helper_damage_work [drm_kms_helper] >> [IGT] fbdev: starting subtest nullptr >> >> RIP: 0010:memcpy_erms+0xa/0x20 >> RSP: 0018:ffffa17d40167d98 EFLAGS: 00010246 >> RAX: ffffa17d4eb7fa80 RBX: ffffa17d40e0aa80 RCX: 00000000000014c0 >> RDX: 0000000000001a40 RSI: ffffa17d40e0b000 RDI: ffffa17d4eb80000 >> RBP: ffffa17d40167e20 R08: 0000000000000000 R09: ffff89522ecff8c0 >> R10: ffffa17d4e4c5000 R11: 0000000000000000 R12: ffffa17d4eb7fa80 >> R13: 0000000000001a40 R14: 000000000000041a R15: ffffa17d40167e30 >> FS: 0000000000000000(0000) GS:ffff895257380000(0000) >> knlGS:0000000000000000 >> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> CR2: ffffa17d40e0b000 CR3: 00000001eaeca006 CR4: 00000000001706e0 >> Call Trace: >> <TASK> >> ? drm_fbdev_generic_helper_fb_dirty+0x207/0x330 [drm_kms_helper] >> drm_fb_helper_damage_work+0x8f/0x170 [drm_kms_helper] >> process_one_work+0x21f/0x430 >> worker_thread+0x4e/0x3c0 >> ? __pfx_worker_thread+0x10/0x10 >> kthread+0xf4/0x120 >> ? __pfx_kthread+0x10/0x10 >> ret_from_fork+0x2c/0x50 >> </TASK> >> CR2: ffffa17d40e0b000 >> ---[ end trace 0000000000000000 ]--- >> >> The indirect reason is drm_fb_helper_memory_range_to_clip() generate >> damage >> rectangles which partially or completely go out of the active display >> area. >> The second of argument 'off' is passing from the user-space, this >> will lead >> to the out-of-bound if it is large than (fb_height + 1) * fb_pitches; >> while >> DIV_ROUND_UP() may also controbute to error by 1. >> >> This patch will add code to restrict the damage rect computed go >> beyond of >> the last line of the framebuffer. >> >> Signed-off-by: Sui Jingfeng <suijingfeng@loongson.cn> >> --- >> drivers/gpu/drm/drm_fb_helper.c | 16 ++++++++++++---- >> drivers/gpu/drm/drm_fbdev_generic.c | 2 +- >> 2 files changed, 13 insertions(+), 5 deletions(-) >> >> diff --git a/drivers/gpu/drm/drm_fb_helper.c >> b/drivers/gpu/drm/drm_fb_helper.c >> index 64458982be40..6bb1b8b27d7a 100644 >> --- a/drivers/gpu/drm/drm_fb_helper.c >> +++ b/drivers/gpu/drm/drm_fb_helper.c >> @@ -641,19 +641,27 @@ static void drm_fb_helper_damage(struct >> drm_fb_helper *helper, u32 x, u32 y, >> static void drm_fb_helper_memory_range_to_clip(struct fb_info >> *info, off_t off, size_t len, >> struct drm_rect *clip) >> { >> + u32 line_length = info->fix.line_length; >> + u32 fb_height = info->var.yres; >> off_t end = off + len; >> u32 x1 = 0; >> - u32 y1 = off / info->fix.line_length; >> + u32 y1 = off / line_length; >> u32 x2 = info->var.xres; >> - u32 y2 = DIV_ROUND_UP(end, info->fix.line_length); >> + u32 y2 = DIV_ROUND_UP(end, line_length); >> + >> + /* Don't allow any of them beyond the bottom bound of display >> area */ >> + if (y1 > fb_height) >> + y1 = fb_height; >> + if (y2 > fb_height) >> + y2 = fb_height; >> if ((y2 - y1) == 1) { >> /* >> * We've only written to a single scanline. Try to reduce >> * the number of horizontal pixels that need an update. >> */ >> - off_t bit_off = (off % info->fix.line_length) * 8; >> - off_t bit_end = (end % info->fix.line_length) * 8; >> + off_t bit_off = (off % line_length) * 8; >> + off_t bit_end = (end % line_length) * 8; > > Please scratch all these changes. The current code should work as > intended. Only the generic fbdev emulation uses this code and it > should really be moved there at some point. Are you meant that we should remove all these changes in drivers/gpu/drm/drm_fb_helper.c ? But this changes are helps to prevent the damage box computed go out of bound, the bound of the displayable shadow buffer on multiple display case. It is the minimum width x height which could be fit in for all display/minotor. For example, one is 1920x1080 monitor, another is 1280x800 monitor. connected to the motherboard simultaneously. Then, 1920x1080x4 (suppose we are using the XRGB) scanout buffer will be allocate by the GEM backend. But the the actual display area is 1280x800. This is true at least for my driver on my platform, In this case, ``` info->var.xres ==1280; info->var.yres == 800; ``` If don't restrict this, the damage box computed out of the bound of (0, 0) ~ (1280, 800) rectangle. a 1920x1080 damage box will came out. When running fbdev test of IGT, the smaller screen display will be OK. but the larger screen, the area outsize of 1280x800 will also be written. The background color became completely white from completely black before carry out the test, luckily, linux kernel do not hung, this time. On multi-screen case, we still need to restrict the damage box computed, Do not go out of 1280x800, right? > >> x1 = bit_off / info->var.bits_per_pixel; >> x2 = DIV_ROUND_UP(bit_end, info->var.bits_per_pixel); >> diff --git a/drivers/gpu/drm/drm_fbdev_generic.c >> b/drivers/gpu/drm/drm_fbdev_generic.c >> index 8e5148bf40bb..b057cfbba938 100644 >> --- a/drivers/gpu/drm/drm_fbdev_generic.c >> +++ b/drivers/gpu/drm/drm_fbdev_generic.c >> @@ -94,7 +94,7 @@ static int drm_fbdev_generic_helper_fb_probe(struct >> drm_fb_helper *fb_helper, >> fb_helper->buffer = buffer; >> fb_helper->fb = buffer->fb; >> - screen_size = buffer->gem->size; >> + screen_size = sizes->surface_height * buffer->fb->pitches[0]; > > I guess we simply go back to this line. I'd R-b a patch that does > exactly this. > > But some explanation is in order. Maybe you can add this as a comment > to the computation, as it's not obvious: > > The value of screen_size should actually be the size of the gem > buffer. In a physical framebuffer (i.e., video memory), the size would > be a multiple of the page size, but not necessarily a multiple of the > screen resolution. There are also pan fbdev's operations, and we could > possibly use DRM buffers that are not multiples of the screen width. > But the update code requires the use of drm_framebuffer_funcs.dirty, > which takes a clipping rectangle and therefore doesn't work well with > these odd values for screen_size. > > Best regards > Thomas > >> screen_buffer = vzalloc(screen_size); >> if (!screen_buffer) { >> ret = -ENOMEM; >
On Fri, Apr 14, 2023 at 06:58:53PM +0800, Sui Jingfeng wrote: > Hi, > > On 2023/4/14 03:16, Thomas Zimmermann wrote: > > Hi, > > > > thanks for the patch. This is effectively a revert of commit > > 8fbc9af55de0 ("drm/fbdev-generic: Set screen size to size of GEM > > buffer"). Please add a Fixes tag. > > > > Am 13.04.23 um 20:06 schrieb Sui Jingfeng: > > > From: Sui Jingfeng <suijingfeng@loongson.cn> > > > > > > The crazy fbdev test of IGT may write after EOF, which lead to > > > out-of-bound > > > > Please drop 'crazy'. :) > > This is OK. > > By using the world 'crazy', > > I meant that the test is very good and maybe it is written by professional > peoples > > with the guidance by experienced engineer. So that even the corner get > tested. 'thoroughly' would be better word to describe that I think. I think for the other discussions I've covered it all already in the other thread. -Daniel > > > > > > > access for the drm drivers using fbdev-generic. For example, run > > > fbdev test > > > on a x86-64+ast2400 platform with 1680x1050 resolution will cause > > > the linux > > > kernel hang with following call trace: > > > > > > Oops: 0000 [#1] PREEMPT SMP PTI > > > [IGT] fbdev: starting subtest eof > > > Workqueue: events drm_fb_helper_damage_work [drm_kms_helper] > > > [IGT] fbdev: starting subtest nullptr > > > > > > RIP: 0010:memcpy_erms+0xa/0x20 > > > RSP: 0018:ffffa17d40167d98 EFLAGS: 00010246 > > > RAX: ffffa17d4eb7fa80 RBX: ffffa17d40e0aa80 RCX: 00000000000014c0 > > > RDX: 0000000000001a40 RSI: ffffa17d40e0b000 RDI: ffffa17d4eb80000 > > > RBP: ffffa17d40167e20 R08: 0000000000000000 R09: ffff89522ecff8c0 > > > R10: ffffa17d4e4c5000 R11: 0000000000000000 R12: ffffa17d4eb7fa80 > > > R13: 0000000000001a40 R14: 000000000000041a R15: ffffa17d40167e30 > > > FS: 0000000000000000(0000) GS:ffff895257380000(0000) > > > knlGS:0000000000000000 > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > CR2: ffffa17d40e0b000 CR3: 00000001eaeca006 CR4: 00000000001706e0 > > > Call Trace: > > > <TASK> > > > ? drm_fbdev_generic_helper_fb_dirty+0x207/0x330 [drm_kms_helper] > > > drm_fb_helper_damage_work+0x8f/0x170 [drm_kms_helper] > > > process_one_work+0x21f/0x430 > > > worker_thread+0x4e/0x3c0 > > > ? __pfx_worker_thread+0x10/0x10 > > > kthread+0xf4/0x120 > > > ? __pfx_kthread+0x10/0x10 > > > ret_from_fork+0x2c/0x50 > > > </TASK> > > > CR2: ffffa17d40e0b000 > > > ---[ end trace 0000000000000000 ]--- > > > > > > The indirect reason is drm_fb_helper_memory_range_to_clip() generate > > > damage > > > rectangles which partially or completely go out of the active > > > display area. > > > The second of argument 'off' is passing from the user-space, this > > > will lead > > > to the out-of-bound if it is large than (fb_height + 1) * > > > fb_pitches; while > > > DIV_ROUND_UP() may also controbute to error by 1. > > > > > > This patch will add code to restrict the damage rect computed go > > > beyond of > > > the last line of the framebuffer. > > > > > > Signed-off-by: Sui Jingfeng <suijingfeng@loongson.cn> > > > --- > > > drivers/gpu/drm/drm_fb_helper.c | 16 ++++++++++++---- > > > drivers/gpu/drm/drm_fbdev_generic.c | 2 +- > > > 2 files changed, 13 insertions(+), 5 deletions(-) > > > > > > diff --git a/drivers/gpu/drm/drm_fb_helper.c > > > b/drivers/gpu/drm/drm_fb_helper.c > > > index 64458982be40..6bb1b8b27d7a 100644 > > > --- a/drivers/gpu/drm/drm_fb_helper.c > > > +++ b/drivers/gpu/drm/drm_fb_helper.c > > > @@ -641,19 +641,27 @@ static void drm_fb_helper_damage(struct > > > drm_fb_helper *helper, u32 x, u32 y, > > > static void drm_fb_helper_memory_range_to_clip(struct fb_info > > > *info, off_t off, size_t len, > > > struct drm_rect *clip) > > > { > > > + u32 line_length = info->fix.line_length; > > > + u32 fb_height = info->var.yres; > > > off_t end = off + len; > > > u32 x1 = 0; > > > - u32 y1 = off / info->fix.line_length; > > > + u32 y1 = off / line_length; > > > u32 x2 = info->var.xres; > > > - u32 y2 = DIV_ROUND_UP(end, info->fix.line_length); > > > + u32 y2 = DIV_ROUND_UP(end, line_length); > > > + > > > + /* Don't allow any of them beyond the bottom bound of display > > > area */ > > > + if (y1 > fb_height) > > > + y1 = fb_height; > > > + if (y2 > fb_height) > > > + y2 = fb_height; > > > if ((y2 - y1) == 1) { > > > /* > > > * We've only written to a single scanline. Try to reduce > > > * the number of horizontal pixels that need an update. > > > */ > > > - off_t bit_off = (off % info->fix.line_length) * 8; > > > - off_t bit_end = (end % info->fix.line_length) * 8; > > > + off_t bit_off = (off % line_length) * 8; > > > + off_t bit_end = (end % line_length) * 8; > > > > Please scratch all these changes. The current code should work as > > intended. Only the generic fbdev emulation uses this code and it should > > really be moved there at some point. > > > Are you meant that we should remove all these changes in > drivers/gpu/drm/drm_fb_helper.c ? > > > But this changes are helps to prevent the damage box computed go out of > bound, > > the bound of the displayable shadow buffer on multiple display case. > > It is the minimum width x height which could be fit in for all > display/minotor. > > > For example, one is 1920x1080 monitor, another is 1280x800 monitor. > > connected to the motherboard simultaneously. > > > Then, 1920x1080x4 (suppose we are using the XRGB) scanout buffer will be > > allocate by the GEM backend. But the the actual display area is 1280x800. > > This is true at least for my driver on my platform, In this case, > > ``` > > info->var.xres ==1280; > > info->var.yres == 800; > > ``` > > If don't restrict this, the damage box computed out of the bound of (0, 0) > ~ (1280, 800) rectangle. > > a 1920x1080 damage box will came out. > > > When running fbdev test of IGT, the smaller screen display will be OK. > > but the larger screen, the area outsize of 1280x800 will also be written. > > The background color became completely white from completely black before > carry out the test, > > luckily, linux kernel do not hung, this time. > > > On multi-screen case, we still need to restrict the damage box computed, > > Do not go out of 1280x800, right? > > > > > > > x1 = bit_off / info->var.bits_per_pixel; > > > x2 = DIV_ROUND_UP(bit_end, info->var.bits_per_pixel); > > > diff --git a/drivers/gpu/drm/drm_fbdev_generic.c > > > b/drivers/gpu/drm/drm_fbdev_generic.c > > > index 8e5148bf40bb..b057cfbba938 100644 > > > --- a/drivers/gpu/drm/drm_fbdev_generic.c > > > +++ b/drivers/gpu/drm/drm_fbdev_generic.c > > > @@ -94,7 +94,7 @@ static int > > > drm_fbdev_generic_helper_fb_probe(struct drm_fb_helper *fb_helper, > > > fb_helper->buffer = buffer; > > > fb_helper->fb = buffer->fb; > > > - screen_size = buffer->gem->size; > > > + screen_size = sizes->surface_height * buffer->fb->pitches[0]; > > > > I guess we simply go back to this line. I'd R-b a patch that does > > exactly this. > > > > But some explanation is in order. Maybe you can add this as a comment to > > the computation, as it's not obvious: > > > > The value of screen_size should actually be the size of the gem buffer. > > In a physical framebuffer (i.e., video memory), the size would be a > > multiple of the page size, but not necessarily a multiple of the screen > > resolution. There are also pan fbdev's operations, and we could possibly > > use DRM buffers that are not multiples of the screen width. But the > > update code requires the use of drm_framebuffer_funcs.dirty, which takes > > a clipping rectangle and therefore doesn't work well with these odd > > values for screen_size. > > > > Best regards > > Thomas > > > > > screen_buffer = vzalloc(screen_size); > > > if (!screen_buffer) { > > > ret = -ENOMEM; > >
Hi, On 2023/4/16 15:57, Daniel Vetter wrote: > On Fri, Apr 14, 2023 at 06:58:53PM +0800, Sui Jingfeng wrote: >> Hi, >> >> On 2023/4/14 03:16, Thomas Zimmermann wrote: >>> Hi, >>> >>> thanks for the patch. This is effectively a revert of commit >>> 8fbc9af55de0 ("drm/fbdev-generic: Set screen size to size of GEM >>> buffer"). Please add a Fixes tag. >>> >>> Am 13.04.23 um 20:06 schrieb Sui Jingfeng: >>>> From: Sui Jingfeng <suijingfeng@loongson.cn> >>>> >>>> The crazy fbdev test of IGT may write after EOF, which lead to >>>> out-of-bound >>> Please drop 'crazy'. :) >> This is OK. >> >> By using the world 'crazy', >> >> I meant that the test is very good and maybe it is written by professional >> peoples >> >> with the guidance by experienced engineer. So that even the corner get >> tested. > 'thoroughly' would be better word to describe that I think. > > I think for the other discussions I've covered it all already in the other > thread. > -Daniel > Yes, 'thoroughly' is a definitely better word than 'crazy'. I see your reviews in v1 the thread of this patch, I will resend this patch with updates. But I thinks we should wait Thomas Z. for a while. I'm wondering whether he still have some strong feelings toward this, I guess not. thanks, :-) >> >>>> access for the drm drivers using fbdev-generic. For example, run >>>> fbdev test >>>> on a x86-64+ast2400 platform with 1680x1050 resolution will cause >>>> the linux >>>> kernel hang with following call trace: >>>> >>>> Oops: 0000 [#1] PREEMPT SMP PTI >>>> [IGT] fbdev: starting subtest eof >>>> Workqueue: events drm_fb_helper_damage_work [drm_kms_helper] >>>> [IGT] fbdev: starting subtest nullptr >>>> >>>> RIP: 0010:memcpy_erms+0xa/0x20 >>>> RSP: 0018:ffffa17d40167d98 EFLAGS: 00010246 >>>> RAX: ffffa17d4eb7fa80 RBX: ffffa17d40e0aa80 RCX: 00000000000014c0 >>>> RDX: 0000000000001a40 RSI: ffffa17d40e0b000 RDI: ffffa17d4eb80000 >>>> RBP: ffffa17d40167e20 R08: 0000000000000000 R09: ffff89522ecff8c0 >>>> R10: ffffa17d4e4c5000 R11: 0000000000000000 R12: ffffa17d4eb7fa80 >>>> R13: 0000000000001a40 R14: 000000000000041a R15: ffffa17d40167e30 >>>> FS: 0000000000000000(0000) GS:ffff895257380000(0000) >>>> knlGS:0000000000000000 >>>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>>> CR2: ffffa17d40e0b000 CR3: 00000001eaeca006 CR4: 00000000001706e0 >>>> Call Trace: >>>> <TASK> >>>> ? drm_fbdev_generic_helper_fb_dirty+0x207/0x330 [drm_kms_helper] >>>> drm_fb_helper_damage_work+0x8f/0x170 [drm_kms_helper] >>>> process_one_work+0x21f/0x430 >>>> worker_thread+0x4e/0x3c0 >>>> ? __pfx_worker_thread+0x10/0x10 >>>> kthread+0xf4/0x120 >>>> ? __pfx_kthread+0x10/0x10 >>>> ret_from_fork+0x2c/0x50 >>>> </TASK> >>>> CR2: ffffa17d40e0b000 >>>> ---[ end trace 0000000000000000 ]--- >>>> >>>> The indirect reason is drm_fb_helper_memory_range_to_clip() generate >>>> damage >>>> rectangles which partially or completely go out of the active >>>> display area. >>>> The second of argument 'off' is passing from the user-space, this >>>> will lead >>>> to the out-of-bound if it is large than (fb_height + 1) * >>>> fb_pitches; while >>>> DIV_ROUND_UP() may also controbute to error by 1. >>>> >>>> This patch will add code to restrict the damage rect computed go >>>> beyond of >>>> the last line of the framebuffer. >>>> >>>> Signed-off-by: Sui Jingfeng <suijingfeng@loongson.cn> >>>> --- >>>> drivers/gpu/drm/drm_fb_helper.c | 16 ++++++++++++---- >>>> drivers/gpu/drm/drm_fbdev_generic.c | 2 +- >>>> 2 files changed, 13 insertions(+), 5 deletions(-) >>>> >>>> diff --git a/drivers/gpu/drm/drm_fb_helper.c >>>> b/drivers/gpu/drm/drm_fb_helper.c >>>> index 64458982be40..6bb1b8b27d7a 100644 >>>> --- a/drivers/gpu/drm/drm_fb_helper.c >>>> +++ b/drivers/gpu/drm/drm_fb_helper.c >>>> @@ -641,19 +641,27 @@ static void drm_fb_helper_damage(struct >>>> drm_fb_helper *helper, u32 x, u32 y, >>>> static void drm_fb_helper_memory_range_to_clip(struct fb_info >>>> *info, off_t off, size_t len, >>>> struct drm_rect *clip) >>>> { >>>> + u32 line_length = info->fix.line_length; >>>> + u32 fb_height = info->var.yres; >>>> off_t end = off + len; >>>> u32 x1 = 0; >>>> - u32 y1 = off / info->fix.line_length; >>>> + u32 y1 = off / line_length; >>>> u32 x2 = info->var.xres; >>>> - u32 y2 = DIV_ROUND_UP(end, info->fix.line_length); >>>> + u32 y2 = DIV_ROUND_UP(end, line_length); >>>> + >>>> + /* Don't allow any of them beyond the bottom bound of display >>>> area */ >>>> + if (y1 > fb_height) >>>> + y1 = fb_height; >>>> + if (y2 > fb_height) >>>> + y2 = fb_height; >>>> if ((y2 - y1) == 1) { >>>> /* >>>> * We've only written to a single scanline. Try to reduce >>>> * the number of horizontal pixels that need an update. >>>> */ >>>> - off_t bit_off = (off % info->fix.line_length) * 8; >>>> - off_t bit_end = (end % info->fix.line_length) * 8; >>>> + off_t bit_off = (off % line_length) * 8; >>>> + off_t bit_end = (end % line_length) * 8; >>> Please scratch all these changes. The current code should work as >>> intended. Only the generic fbdev emulation uses this code and it should >>> really be moved there at some point. >> >> Are you meant that we should remove all these changes in >> drivers/gpu/drm/drm_fb_helper.c ? >> >> >> But this changes are helps to prevent the damage box computed go out of >> bound, >> >> the bound of the displayable shadow buffer on multiple display case. >> >> It is the minimum width x height which could be fit in for all >> display/minotor. >> >> >> For example, one is 1920x1080 monitor, another is 1280x800 monitor. >> >> connected to the motherboard simultaneously. >> >> >> Then, 1920x1080x4 (suppose we are using the XRGB) scanout buffer will be >> >> allocate by the GEM backend. But the the actual display area is 1280x800. >> >> This is true at least for my driver on my platform, In this case, >> >> ``` >> >> info->var.xres ==1280; >> >> info->var.yres == 800; >> >> ``` >> >> If don't restrict this, the damage box computed out of the bound of (0, 0) >> ~ (1280, 800) rectangle. >> >> a 1920x1080 damage box will came out. >> >> >> When running fbdev test of IGT, the smaller screen display will be OK. >> >> but the larger screen, the area outsize of 1280x800 will also be written. >> >> The background color became completely white from completely black before >> carry out the test, >> >> luckily, linux kernel do not hung, this time. >> >> >> On multi-screen case, we still need to restrict the damage box computed, >> >> Do not go out of 1280x800, right? >> >> >>>> x1 = bit_off / info->var.bits_per_pixel; >>>> x2 = DIV_ROUND_UP(bit_end, info->var.bits_per_pixel); >>>> diff --git a/drivers/gpu/drm/drm_fbdev_generic.c >>>> b/drivers/gpu/drm/drm_fbdev_generic.c >>>> index 8e5148bf40bb..b057cfbba938 100644 >>>> --- a/drivers/gpu/drm/drm_fbdev_generic.c >>>> +++ b/drivers/gpu/drm/drm_fbdev_generic.c >>>> @@ -94,7 +94,7 @@ static int >>>> drm_fbdev_generic_helper_fb_probe(struct drm_fb_helper *fb_helper, >>>> fb_helper->buffer = buffer; >>>> fb_helper->fb = buffer->fb; >>>> - screen_size = buffer->gem->size; >>>> + screen_size = sizes->surface_height * buffer->fb->pitches[0]; >>> I guess we simply go back to this line. I'd R-b a patch that does >>> exactly this. >>> >>> But some explanation is in order. Maybe you can add this as a comment to >>> the computation, as it's not obvious: >>> >>> The value of screen_size should actually be the size of the gem buffer. >>> In a physical framebuffer (i.e., video memory), the size would be a >>> multiple of the page size, but not necessarily a multiple of the screen >>> resolution. There are also pan fbdev's operations, and we could possibly >>> use DRM buffers that are not multiples of the screen width. But the >>> update code requires the use of drm_framebuffer_funcs.dirty, which takes >>> a clipping rectangle and therefore doesn't work well with these odd >>> values for screen_size. >>> >>> Best regards >>> Thomas >>> >>>> screen_buffer = vzalloc(screen_size); >>>> if (!screen_buffer) { >>>> ret = -ENOMEM;
Hi Am 14.04.23 um 12:58 schrieb Sui Jingfeng: > Hi, > > On 2023/4/14 03:16, Thomas Zimmermann wrote: >> Hi, >> >> thanks for the patch. This is effectively a revert of commit >> 8fbc9af55de0 ("drm/fbdev-generic: Set screen size to size of GEM >> buffer"). Please add a Fixes tag. >> >> Am 13.04.23 um 20:06 schrieb Sui Jingfeng: >>> From: Sui Jingfeng <suijingfeng@loongson.cn> >>> >>> The crazy fbdev test of IGT may write after EOF, which lead to >>> out-of-bound >> >> Please drop 'crazy'. :) > > This is OK. > > By using the world 'crazy', > > I meant that the test is very good and maybe it is written by > professional peoples > > with the guidance by experienced engineer. So that even the corner get > tested. > > >> >>> access for the drm drivers using fbdev-generic. For example, run >>> fbdev test >>> on a x86-64+ast2400 platform with 1680x1050 resolution will cause the >>> linux >>> kernel hang with following call trace: >>> >>> Oops: 0000 [#1] PREEMPT SMP PTI >>> [IGT] fbdev: starting subtest eof >>> Workqueue: events drm_fb_helper_damage_work [drm_kms_helper] >>> [IGT] fbdev: starting subtest nullptr >>> >>> RIP: 0010:memcpy_erms+0xa/0x20 >>> RSP: 0018:ffffa17d40167d98 EFLAGS: 00010246 >>> RAX: ffffa17d4eb7fa80 RBX: ffffa17d40e0aa80 RCX: 00000000000014c0 >>> RDX: 0000000000001a40 RSI: ffffa17d40e0b000 RDI: ffffa17d4eb80000 >>> RBP: ffffa17d40167e20 R08: 0000000000000000 R09: ffff89522ecff8c0 >>> R10: ffffa17d4e4c5000 R11: 0000000000000000 R12: ffffa17d4eb7fa80 >>> R13: 0000000000001a40 R14: 000000000000041a R15: ffffa17d40167e30 >>> FS: 0000000000000000(0000) GS:ffff895257380000(0000) >>> knlGS:0000000000000000 >>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>> CR2: ffffa17d40e0b000 CR3: 00000001eaeca006 CR4: 00000000001706e0 >>> Call Trace: >>> <TASK> >>> ? drm_fbdev_generic_helper_fb_dirty+0x207/0x330 [drm_kms_helper] >>> drm_fb_helper_damage_work+0x8f/0x170 [drm_kms_helper] >>> process_one_work+0x21f/0x430 >>> worker_thread+0x4e/0x3c0 >>> ? __pfx_worker_thread+0x10/0x10 >>> kthread+0xf4/0x120 >>> ? __pfx_kthread+0x10/0x10 >>> ret_from_fork+0x2c/0x50 >>> </TASK> >>> CR2: ffffa17d40e0b000 >>> ---[ end trace 0000000000000000 ]--- >>> >>> The indirect reason is drm_fb_helper_memory_range_to_clip() generate >>> damage >>> rectangles which partially or completely go out of the active display >>> area. >>> The second of argument 'off' is passing from the user-space, this >>> will lead >>> to the out-of-bound if it is large than (fb_height + 1) * fb_pitches; >>> while >>> DIV_ROUND_UP() may also controbute to error by 1. >>> >>> This patch will add code to restrict the damage rect computed go >>> beyond of >>> the last line of the framebuffer. >>> >>> Signed-off-by: Sui Jingfeng <suijingfeng@loongson.cn> >>> --- >>> drivers/gpu/drm/drm_fb_helper.c | 16 ++++++++++++---- >>> drivers/gpu/drm/drm_fbdev_generic.c | 2 +- >>> 2 files changed, 13 insertions(+), 5 deletions(-) >>> >>> diff --git a/drivers/gpu/drm/drm_fb_helper.c >>> b/drivers/gpu/drm/drm_fb_helper.c >>> index 64458982be40..6bb1b8b27d7a 100644 >>> --- a/drivers/gpu/drm/drm_fb_helper.c >>> +++ b/drivers/gpu/drm/drm_fb_helper.c >>> @@ -641,19 +641,27 @@ static void drm_fb_helper_damage(struct >>> drm_fb_helper *helper, u32 x, u32 y, >>> static void drm_fb_helper_memory_range_to_clip(struct fb_info >>> *info, off_t off, size_t len, >>> struct drm_rect *clip) >>> { >>> + u32 line_length = info->fix.line_length; >>> + u32 fb_height = info->var.yres; >>> off_t end = off + len; >>> u32 x1 = 0; >>> - u32 y1 = off / info->fix.line_length; >>> + u32 y1 = off / line_length; >>> u32 x2 = info->var.xres; >>> - u32 y2 = DIV_ROUND_UP(end, info->fix.line_length); >>> + u32 y2 = DIV_ROUND_UP(end, line_length); >>> + >>> + /* Don't allow any of them beyond the bottom bound of display >>> area */ >>> + if (y1 > fb_height) >>> + y1 = fb_height; >>> + if (y2 > fb_height) >>> + y2 = fb_height; >>> if ((y2 - y1) == 1) { >>> /* >>> * We've only written to a single scanline. Try to reduce >>> * the number of horizontal pixels that need an update. >>> */ >>> - off_t bit_off = (off % info->fix.line_length) * 8; >>> - off_t bit_end = (end % info->fix.line_length) * 8; >>> + off_t bit_off = (off % line_length) * 8; >>> + off_t bit_end = (end % line_length) * 8; >> >> Please scratch all these changes. The current code should work as >> intended. Only the generic fbdev emulation uses this code and it >> should really be moved there at some point. > > > Are you meant that we should remove all these changes in > drivers/gpu/drm/drm_fb_helper.c ? As Daniel mentioned, there's the discussion in the other thread. I don't want to reopen it here. Just to summarize: I'm not convinced that this should be DRM code because it can be shared with other fbdev drivers. [...] >>> diff --git a/drivers/gpu/drm/drm_fbdev_generic.c >>> b/drivers/gpu/drm/drm_fbdev_generic.c >>> index 8e5148bf40bb..b057cfbba938 100644 >>> --- a/drivers/gpu/drm/drm_fbdev_generic.c >>> +++ b/drivers/gpu/drm/drm_fbdev_generic.c >>> @@ -94,7 +94,7 @@ static int drm_fbdev_generic_helper_fb_probe(struct >>> drm_fb_helper *fb_helper, >>> fb_helper->buffer = buffer; >>> fb_helper->fb = buffer->fb; >>> - screen_size = buffer->gem->size; >>> + screen_size = sizes->surface_height * buffer->fb->pitches[0]; This has been bothering me over the weekend. And I think it's because what we want the screen_size to be heigth * pitch, but the mmap'ed memory is still at page granularity. Therefore... [...] >> >>> screen_buffer = vzalloc(screen_size); ... this line should explicitly allocate multiples of pages. Something like /* allocate page-size multiples for mmap */ vzalloc(PAGE_ALIGN(screen_size)) It has not been a bug so far because vzalloc() always returns full pages IIRC. It's still worth fixing. Best regards Thomas >>> if (!screen_buffer) { >>> ret = -ENOMEM; >>
Hi, On 2023/4/17 15:29, Thomas Zimmermann wrote: > Hi > > Am 14.04.23 um 12:58 schrieb Sui Jingfeng: >> Hi, >> >> On 2023/4/14 03:16, Thomas Zimmermann wrote: >>> Hi, >>> >>> thanks for the patch. This is effectively a revert of commit >>> 8fbc9af55de0 ("drm/fbdev-generic: Set screen size to size of GEM >>> buffer"). Please add a Fixes tag. >>> >>> Am 13.04.23 um 20:06 schrieb Sui Jingfeng: >>>> From: Sui Jingfeng <suijingfeng@loongson.cn> >>>> >>>> The crazy fbdev test of IGT may write after EOF, which lead to >>>> out-of-bound >>> >>> Please drop 'crazy'. :) >> >> This is OK. >> >> By using the world 'crazy', >> >> I meant that the test is very good and maybe it is written by >> professional peoples >> >> with the guidance by experienced engineer. So that even the corner >> get tested. >> >> >>> >>>> access for the drm drivers using fbdev-generic. For example, run >>>> fbdev test >>>> on a x86-64+ast2400 platform with 1680x1050 resolution will cause >>>> the linux >>>> kernel hang with following call trace: >>>> >>>> Oops: 0000 [#1] PREEMPT SMP PTI >>>> [IGT] fbdev: starting subtest eof >>>> Workqueue: events drm_fb_helper_damage_work [drm_kms_helper] >>>> [IGT] fbdev: starting subtest nullptr >>>> >>>> RIP: 0010:memcpy_erms+0xa/0x20 >>>> RSP: 0018:ffffa17d40167d98 EFLAGS: 00010246 >>>> RAX: ffffa17d4eb7fa80 RBX: ffffa17d40e0aa80 RCX: 00000000000014c0 >>>> RDX: 0000000000001a40 RSI: ffffa17d40e0b000 RDI: ffffa17d4eb80000 >>>> RBP: ffffa17d40167e20 R08: 0000000000000000 R09: ffff89522ecff8c0 >>>> R10: ffffa17d4e4c5000 R11: 0000000000000000 R12: ffffa17d4eb7fa80 >>>> R13: 0000000000001a40 R14: 000000000000041a R15: ffffa17d40167e30 >>>> FS: 0000000000000000(0000) GS:ffff895257380000(0000) >>>> knlGS:0000000000000000 >>>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>>> CR2: ffffa17d40e0b000 CR3: 00000001eaeca006 CR4: 00000000001706e0 >>>> Call Trace: >>>> <TASK> >>>> ? drm_fbdev_generic_helper_fb_dirty+0x207/0x330 [drm_kms_helper] >>>> drm_fb_helper_damage_work+0x8f/0x170 [drm_kms_helper] >>>> process_one_work+0x21f/0x430 >>>> worker_thread+0x4e/0x3c0 >>>> ? __pfx_worker_thread+0x10/0x10 >>>> kthread+0xf4/0x120 >>>> ? __pfx_kthread+0x10/0x10 >>>> ret_from_fork+0x2c/0x50 >>>> </TASK> >>>> CR2: ffffa17d40e0b000 >>>> ---[ end trace 0000000000000000 ]--- >>>> >>>> The indirect reason is drm_fb_helper_memory_range_to_clip() >>>> generate damage >>>> rectangles which partially or completely go out of the active >>>> display area. >>>> The second of argument 'off' is passing from the user-space, this >>>> will lead >>>> to the out-of-bound if it is large than (fb_height + 1) * >>>> fb_pitches; while >>>> DIV_ROUND_UP() may also controbute to error by 1. >>>> >>>> This patch will add code to restrict the damage rect computed go >>>> beyond of >>>> the last line of the framebuffer. >>>> >>>> Signed-off-by: Sui Jingfeng <suijingfeng@loongson.cn> >>>> --- >>>> drivers/gpu/drm/drm_fb_helper.c | 16 ++++++++++++---- >>>> drivers/gpu/drm/drm_fbdev_generic.c | 2 +- >>>> 2 files changed, 13 insertions(+), 5 deletions(-) >>>> >>>> diff --git a/drivers/gpu/drm/drm_fb_helper.c >>>> b/drivers/gpu/drm/drm_fb_helper.c >>>> index 64458982be40..6bb1b8b27d7a 100644 >>>> --- a/drivers/gpu/drm/drm_fb_helper.c >>>> +++ b/drivers/gpu/drm/drm_fb_helper.c >>>> @@ -641,19 +641,27 @@ static void drm_fb_helper_damage(struct >>>> drm_fb_helper *helper, u32 x, u32 y, >>>> static void drm_fb_helper_memory_range_to_clip(struct fb_info >>>> *info, off_t off, size_t len, >>>> struct drm_rect *clip) >>>> { >>>> + u32 line_length = info->fix.line_length; >>>> + u32 fb_height = info->var.yres; >>>> off_t end = off + len; >>>> u32 x1 = 0; >>>> - u32 y1 = off / info->fix.line_length; >>>> + u32 y1 = off / line_length; >>>> u32 x2 = info->var.xres; >>>> - u32 y2 = DIV_ROUND_UP(end, info->fix.line_length); >>>> + u32 y2 = DIV_ROUND_UP(end, line_length); >>>> + >>>> + /* Don't allow any of them beyond the bottom bound of display >>>> area */ >>>> + if (y1 > fb_height) >>>> + y1 = fb_height; >>>> + if (y2 > fb_height) >>>> + y2 = fb_height; >>>> if ((y2 - y1) == 1) { >>>> /* >>>> * We've only written to a single scanline. Try to reduce >>>> * the number of horizontal pixels that need an update. >>>> */ >>>> - off_t bit_off = (off % info->fix.line_length) * 8; >>>> - off_t bit_end = (end % info->fix.line_length) * 8; >>>> + off_t bit_off = (off % line_length) * 8; >>>> + off_t bit_end = (end % line_length) * 8; >>> >>> Please scratch all these changes. The current code should work as >>> intended. Only the generic fbdev emulation uses this code and it >>> should really be moved there at some point. >> >> >> Are you meant that we should remove all these changes in >> drivers/gpu/drm/drm_fb_helper.c ? > > As Daniel mentioned, there's the discussion in the other thread. I > don't want to reopen it here. Just to summarize: I'm not convinced > that this should be DRM code because it can be shared with other fbdev > drivers. > > [...] > >>>> diff --git a/drivers/gpu/drm/drm_fbdev_generic.c >>>> b/drivers/gpu/drm/drm_fbdev_generic.c >>>> index 8e5148bf40bb..b057cfbba938 100644 >>>> --- a/drivers/gpu/drm/drm_fbdev_generic.c >>>> +++ b/drivers/gpu/drm/drm_fbdev_generic.c >>>> @@ -94,7 +94,7 @@ static int >>>> drm_fbdev_generic_helper_fb_probe(struct drm_fb_helper *fb_helper, >>>> fb_helper->buffer = buffer; >>>> fb_helper->fb = buffer->fb; >>>> - screen_size = buffer->gem->size; >>>> + screen_size = sizes->surface_height * buffer->fb->pitches[0]; > > This has been bothering me over the weekend. And I think it's because > what we want the screen_size to be heigth * pitch, but the mmap'ed > memory is still at page granularity. Therefore... > Yeah, this bug is not that simple as it seems, I will drop the controversy part, leave it there, it may need more time to rethink about it. Thanks for reviewing, don't be so tired... > [...] >>> >>>> screen_buffer = vzalloc(screen_size); > > ... this line should explicitly allocate multiples of pages. Something > like > > /* allocate page-size multiples for mmap */ > vzalloc(PAGE_ALIGN(screen_size)) > > It has not been a bug so far because vzalloc() always returns full > pages IIRC. It's still worth fixing. > > Best regards > Thomas > > >>>> if (!screen_buffer) { >>>> ret = -ENOMEM; >>> >
On Mon, Apr 17, 2023 at 09:29:07AM +0200, Thomas Zimmermann wrote: > Hi > > Am 14.04.23 um 12:58 schrieb Sui Jingfeng: > > Hi, > > > > On 2023/4/14 03:16, Thomas Zimmermann wrote: > > > Hi, > > > > > > thanks for the patch. This is effectively a revert of commit > > > 8fbc9af55de0 ("drm/fbdev-generic: Set screen size to size of GEM > > > buffer"). Please add a Fixes tag. > > > > > > Am 13.04.23 um 20:06 schrieb Sui Jingfeng: > > > > From: Sui Jingfeng <suijingfeng@loongson.cn> > > > > > > > > The crazy fbdev test of IGT may write after EOF, which lead to > > > > out-of-bound > > > > > > Please drop 'crazy'. :) > > > > This is OK. > > > > By using the world 'crazy', > > > > I meant that the test is very good and maybe it is written by > > professional peoples > > > > with the guidance by experienced engineer. So that even the corner get > > tested. > > > > > > > > > > > access for the drm drivers using fbdev-generic. For example, run > > > > fbdev test > > > > on a x86-64+ast2400 platform with 1680x1050 resolution will > > > > cause the linux > > > > kernel hang with following call trace: > > > > > > > > Oops: 0000 [#1] PREEMPT SMP PTI > > > > [IGT] fbdev: starting subtest eof > > > > Workqueue: events drm_fb_helper_damage_work [drm_kms_helper] > > > > [IGT] fbdev: starting subtest nullptr > > > > > > > > RIP: 0010:memcpy_erms+0xa/0x20 > > > > RSP: 0018:ffffa17d40167d98 EFLAGS: 00010246 > > > > RAX: ffffa17d4eb7fa80 RBX: ffffa17d40e0aa80 RCX: 00000000000014c0 > > > > RDX: 0000000000001a40 RSI: ffffa17d40e0b000 RDI: ffffa17d4eb80000 > > > > RBP: ffffa17d40167e20 R08: 0000000000000000 R09: ffff89522ecff8c0 > > > > R10: ffffa17d4e4c5000 R11: 0000000000000000 R12: ffffa17d4eb7fa80 > > > > R13: 0000000000001a40 R14: 000000000000041a R15: ffffa17d40167e30 > > > > FS: 0000000000000000(0000) GS:ffff895257380000(0000) > > > > knlGS:0000000000000000 > > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > > CR2: ffffa17d40e0b000 CR3: 00000001eaeca006 CR4: 00000000001706e0 > > > > Call Trace: > > > > <TASK> > > > > ? drm_fbdev_generic_helper_fb_dirty+0x207/0x330 [drm_kms_helper] > > > > drm_fb_helper_damage_work+0x8f/0x170 [drm_kms_helper] > > > > process_one_work+0x21f/0x430 > > > > worker_thread+0x4e/0x3c0 > > > > ? __pfx_worker_thread+0x10/0x10 > > > > kthread+0xf4/0x120 > > > > ? __pfx_kthread+0x10/0x10 > > > > ret_from_fork+0x2c/0x50 > > > > </TASK> > > > > CR2: ffffa17d40e0b000 > > > > ---[ end trace 0000000000000000 ]--- > > > > > > > > The indirect reason is drm_fb_helper_memory_range_to_clip() > > > > generate damage > > > > rectangles which partially or completely go out of the active > > > > display area. > > > > The second of argument 'off' is passing from the user-space, > > > > this will lead > > > > to the out-of-bound if it is large than (fb_height + 1) * > > > > fb_pitches; while > > > > DIV_ROUND_UP() may also controbute to error by 1. > > > > > > > > This patch will add code to restrict the damage rect computed go > > > > beyond of > > > > the last line of the framebuffer. > > > > > > > > Signed-off-by: Sui Jingfeng <suijingfeng@loongson.cn> > > > > --- > > > > drivers/gpu/drm/drm_fb_helper.c | 16 ++++++++++++---- > > > > drivers/gpu/drm/drm_fbdev_generic.c | 2 +- > > > > 2 files changed, 13 insertions(+), 5 deletions(-) > > > > > > > > diff --git a/drivers/gpu/drm/drm_fb_helper.c > > > > b/drivers/gpu/drm/drm_fb_helper.c > > > > index 64458982be40..6bb1b8b27d7a 100644 > > > > --- a/drivers/gpu/drm/drm_fb_helper.c > > > > +++ b/drivers/gpu/drm/drm_fb_helper.c > > > > @@ -641,19 +641,27 @@ static void drm_fb_helper_damage(struct > > > > drm_fb_helper *helper, u32 x, u32 y, > > > > static void drm_fb_helper_memory_range_to_clip(struct fb_info > > > > *info, off_t off, size_t len, > > > > struct drm_rect *clip) > > > > { > > > > + u32 line_length = info->fix.line_length; > > > > + u32 fb_height = info->var.yres; > > > > off_t end = off + len; > > > > u32 x1 = 0; > > > > - u32 y1 = off / info->fix.line_length; > > > > + u32 y1 = off / line_length; > > > > u32 x2 = info->var.xres; > > > > - u32 y2 = DIV_ROUND_UP(end, info->fix.line_length); > > > > + u32 y2 = DIV_ROUND_UP(end, line_length); > > > > + > > > > + /* Don't allow any of them beyond the bottom bound of > > > > display area */ > > > > + if (y1 > fb_height) > > > > + y1 = fb_height; > > > > + if (y2 > fb_height) > > > > + y2 = fb_height; > > > > if ((y2 - y1) == 1) { > > > > /* > > > > * We've only written to a single scanline. Try to reduce > > > > * the number of horizontal pixels that need an update. > > > > */ > > > > - off_t bit_off = (off % info->fix.line_length) * 8; > > > > - off_t bit_end = (end % info->fix.line_length) * 8; > > > > + off_t bit_off = (off % line_length) * 8; > > > > + off_t bit_end = (end % line_length) * 8; > > > > > > Please scratch all these changes. The current code should work as > > > intended. Only the generic fbdev emulation uses this code and it > > > should really be moved there at some point. > > > > > > Are you meant that we should remove all these changes in > > drivers/gpu/drm/drm_fb_helper.c ? > > As Daniel mentioned, there's the discussion in the other thread. I don't > want to reopen it here. Just to summarize: I'm not convinced that this > should be DRM code because it can be shared with other fbdev drivers. > > [...] > > > > > diff --git a/drivers/gpu/drm/drm_fbdev_generic.c > > > > b/drivers/gpu/drm/drm_fbdev_generic.c > > > > index 8e5148bf40bb..b057cfbba938 100644 > > > > --- a/drivers/gpu/drm/drm_fbdev_generic.c > > > > +++ b/drivers/gpu/drm/drm_fbdev_generic.c > > > > @@ -94,7 +94,7 @@ static int > > > > drm_fbdev_generic_helper_fb_probe(struct drm_fb_helper > > > > *fb_helper, > > > > fb_helper->buffer = buffer; > > > > fb_helper->fb = buffer->fb; > > > > - screen_size = buffer->gem->size; > > > > + screen_size = sizes->surface_height * buffer->fb->pitches[0]; > > This has been bothering me over the weekend. And I think it's because what > we want the screen_size to be heigth * pitch, but the mmap'ed memory is > still at page granularity. Therefore... > > [...] > > > > > > > screen_buffer = vzalloc(screen_size); > > ... this line should explicitly allocate multiples of pages. Something like > > /* allocate page-size multiples for mmap */ > vzalloc(PAGE_ALIGN(screen_size)) > > It has not been a bug so far because vzalloc() always returns full pages > IIRC. It's still worth fixing. So gem_bo are supposed to be at least PAGE_SIZE aligned. So maybe we just put a comment in here why this assumption holds, and reinforce it with a WARN_ON? I think that would address the concerns here? But I concur with Sui that this is a separate issue which should be sorted out in a separate patch. -Daniel > > Best regards > Thomas > > > > > > if (!screen_buffer) { > > > > ret = -ENOMEM; > > > > > -- > Thomas Zimmermann > Graphics Driver Developer > SUSE Software Solutions Germany GmbH > Maxfeldstr. 5, 90409 Nürnberg, Germany > (HRB 36809, AG Nürnberg) > Geschäftsführer: Ivo Totev
Hi, On 2023/4/17 15:29, Thomas Zimmermann wrote: > Hi > > Am 14.04.23 um 12:58 schrieb Sui Jingfeng: >> Hi, >> >> On 2023/4/14 03:16, Thomas Zimmermann wrote: >>> Hi, >>> >>> thanks for the patch. This is effectively a revert of commit >>> 8fbc9af55de0 ("drm/fbdev-generic: Set screen size to size of GEM >>> buffer"). Please add a Fixes tag. >>> >>> Am 13.04.23 um 20:06 schrieb Sui Jingfeng: >>>> From: Sui Jingfeng <suijingfeng@loongson.cn> >>>> >>>> The crazy fbdev test of IGT may write after EOF, which lead to >>>> out-of-bound >>> >>> Please drop 'crazy'. :) >> >> This is OK. >> >> By using the world 'crazy', >> >> I meant that the test is very good and maybe it is written by >> professional peoples >> >> with the guidance by experienced engineer. So that even the corner >> get tested. >> >> >>> >>>> access for the drm drivers using fbdev-generic. For example, run >>>> fbdev test >>>> on a x86-64+ast2400 platform with 1680x1050 resolution will cause >>>> the linux >>>> kernel hang with following call trace: >>>> >>>> Oops: 0000 [#1] PREEMPT SMP PTI >>>> [IGT] fbdev: starting subtest eof >>>> Workqueue: events drm_fb_helper_damage_work [drm_kms_helper] >>>> [IGT] fbdev: starting subtest nullptr >>>> >>>> RIP: 0010:memcpy_erms+0xa/0x20 >>>> RSP: 0018:ffffa17d40167d98 EFLAGS: 00010246 >>>> RAX: ffffa17d4eb7fa80 RBX: ffffa17d40e0aa80 RCX: 00000000000014c0 >>>> RDX: 0000000000001a40 RSI: ffffa17d40e0b000 RDI: ffffa17d4eb80000 >>>> RBP: ffffa17d40167e20 R08: 0000000000000000 R09: ffff89522ecff8c0 >>>> R10: ffffa17d4e4c5000 R11: 0000000000000000 R12: ffffa17d4eb7fa80 >>>> R13: 0000000000001a40 R14: 000000000000041a R15: ffffa17d40167e30 >>>> FS: 0000000000000000(0000) GS:ffff895257380000(0000) >>>> knlGS:0000000000000000 >>>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>>> CR2: ffffa17d40e0b000 CR3: 00000001eaeca006 CR4: 00000000001706e0 >>>> Call Trace: >>>> <TASK> >>>> ? drm_fbdev_generic_helper_fb_dirty+0x207/0x330 [drm_kms_helper] >>>> drm_fb_helper_damage_work+0x8f/0x170 [drm_kms_helper] >>>> process_one_work+0x21f/0x430 >>>> worker_thread+0x4e/0x3c0 >>>> ? __pfx_worker_thread+0x10/0x10 >>>> kthread+0xf4/0x120 >>>> ? __pfx_kthread+0x10/0x10 >>>> ret_from_fork+0x2c/0x50 >>>> </TASK> >>>> CR2: ffffa17d40e0b000 >>>> ---[ end trace 0000000000000000 ]--- >>>> >>>> The indirect reason is drm_fb_helper_memory_range_to_clip() >>>> generate damage >>>> rectangles which partially or completely go out of the active >>>> display area. >>>> The second of argument 'off' is passing from the user-space, this >>>> will lead >>>> to the out-of-bound if it is large than (fb_height + 1) * >>>> fb_pitches; while >>>> DIV_ROUND_UP() may also controbute to error by 1. >>>> >>>> This patch will add code to restrict the damage rect computed go >>>> beyond of >>>> the last line of the framebuffer. >>>> >>>> Signed-off-by: Sui Jingfeng <suijingfeng@loongson.cn> >>>> --- >>>> drivers/gpu/drm/drm_fb_helper.c | 16 ++++++++++++---- >>>> drivers/gpu/drm/drm_fbdev_generic.c | 2 +- >>>> 2 files changed, 13 insertions(+), 5 deletions(-) >>>> >>>> diff --git a/drivers/gpu/drm/drm_fb_helper.c >>>> b/drivers/gpu/drm/drm_fb_helper.c >>>> index 64458982be40..6bb1b8b27d7a 100644 >>>> --- a/drivers/gpu/drm/drm_fb_helper.c >>>> +++ b/drivers/gpu/drm/drm_fb_helper.c >>>> @@ -641,19 +641,27 @@ static void drm_fb_helper_damage(struct >>>> drm_fb_helper *helper, u32 x, u32 y, >>>> static void drm_fb_helper_memory_range_to_clip(struct fb_info >>>> *info, off_t off, size_t len, >>>> struct drm_rect *clip) >>>> { >>>> + u32 line_length = info->fix.line_length; >>>> + u32 fb_height = info->var.yres; >>>> off_t end = off + len; >>>> u32 x1 = 0; >>>> - u32 y1 = off / info->fix.line_length; >>>> + u32 y1 = off / line_length; >>>> u32 x2 = info->var.xres; >>>> - u32 y2 = DIV_ROUND_UP(end, info->fix.line_length); >>>> + u32 y2 = DIV_ROUND_UP(end, line_length); >>>> + >>>> + /* Don't allow any of them beyond the bottom bound of display >>>> area */ >>>> + if (y1 > fb_height) >>>> + y1 = fb_height; >>>> + if (y2 > fb_height) >>>> + y2 = fb_height; >>>> if ((y2 - y1) == 1) { >>>> /* >>>> * We've only written to a single scanline. Try to reduce >>>> * the number of horizontal pixels that need an update. >>>> */ >>>> - off_t bit_off = (off % info->fix.line_length) * 8; >>>> - off_t bit_end = (end % info->fix.line_length) * 8; >>>> + off_t bit_off = (off % line_length) * 8; >>>> + off_t bit_end = (end % line_length) * 8; >>> >>> Please scratch all these changes. The current code should work as >>> intended. Only the generic fbdev emulation uses this code and it >>> should really be moved there at some point. >> >> >> Are you meant that we should remove all these changes in >> drivers/gpu/drm/drm_fb_helper.c ? > > As Daniel mentioned, there's the discussion in the other thread. I > don't want to reopen it here. Just to summarize: I'm not convinced > that this should be DRM code because it can be shared with other fbdev > drivers. > > [...] > >>>> diff --git a/drivers/gpu/drm/drm_fbdev_generic.c >>>> b/drivers/gpu/drm/drm_fbdev_generic.c >>>> index 8e5148bf40bb..b057cfbba938 100644 >>>> --- a/drivers/gpu/drm/drm_fbdev_generic.c >>>> +++ b/drivers/gpu/drm/drm_fbdev_generic.c >>>> @@ -94,7 +94,7 @@ static int >>>> drm_fbdev_generic_helper_fb_probe(struct drm_fb_helper *fb_helper, >>>> fb_helper->buffer = buffer; >>>> fb_helper->fb = buffer->fb; >>>> - screen_size = buffer->gem->size; >>>> + screen_size = sizes->surface_height * buffer->fb->pitches[0]; > > This has been bothering me over the weekend. And I think it's because > what we want the screen_size to be heigth * pitch, but the mmap'ed > memory is still at page granularity. Therefore... > > [...] >>> >>>> screen_buffer = vzalloc(screen_size); > > ... this line should explicitly allocate multiples of pages. Something > like > > /* allocate page-size multiples for mmap */ > vzalloc(PAGE_ALIGN(screen_size)) > I just thought about your instruction at here, thanks! But it is already page size aligned if we don't tough it. It is guaranteed by the GEM memory manger, so a previous patch tested by me, is turn out to be a extremely correct? We exposed a page size aligned buffer(even though it is larger than needed) is actually for mmap ? > It has not been a bug so far because vzalloc() always returns full > pages IIRC. It's still worth fixing. > > Best regards > Thomas > > >>>> if (!screen_buffer) { >>>> ret = -ENOMEM; >>> >
On Thu, Apr 20, 2023 at 02:47:24AM +0800, Sui Jingfeng wrote: > Hi, > > On 2023/4/17 15:29, Thomas Zimmermann wrote: > > Hi > > > > Am 14.04.23 um 12:58 schrieb Sui Jingfeng: > > > Hi, > > > > > > On 2023/4/14 03:16, Thomas Zimmermann wrote: > > > > Hi, > > > > > > > > thanks for the patch. This is effectively a revert of commit > > > > 8fbc9af55de0 ("drm/fbdev-generic: Set screen size to size of GEM > > > > buffer"). Please add a Fixes tag. > > > > > > > > Am 13.04.23 um 20:06 schrieb Sui Jingfeng: > > > > > From: Sui Jingfeng <suijingfeng@loongson.cn> > > > > > > > > > > The crazy fbdev test of IGT may write after EOF, which lead > > > > > to out-of-bound > > > > > > > > Please drop 'crazy'. :) > > > > > > This is OK. > > > > > > By using the world 'crazy', > > > > > > I meant that the test is very good and maybe it is written by > > > professional peoples > > > > > > with the guidance by experienced engineer. So that even the corner > > > get tested. > > > > > > > > > > > > > > > access for the drm drivers using fbdev-generic. For example, > > > > > run fbdev test > > > > > on a x86-64+ast2400 platform with 1680x1050 resolution will > > > > > cause the linux > > > > > kernel hang with following call trace: > > > > > > > > > > Oops: 0000 [#1] PREEMPT SMP PTI > > > > > [IGT] fbdev: starting subtest eof > > > > > Workqueue: events drm_fb_helper_damage_work [drm_kms_helper] > > > > > [IGT] fbdev: starting subtest nullptr > > > > > > > > > > RIP: 0010:memcpy_erms+0xa/0x20 > > > > > RSP: 0018:ffffa17d40167d98 EFLAGS: 00010246 > > > > > RAX: ffffa17d4eb7fa80 RBX: ffffa17d40e0aa80 RCX: 00000000000014c0 > > > > > RDX: 0000000000001a40 RSI: ffffa17d40e0b000 RDI: ffffa17d4eb80000 > > > > > RBP: ffffa17d40167e20 R08: 0000000000000000 R09: ffff89522ecff8c0 > > > > > R10: ffffa17d4e4c5000 R11: 0000000000000000 R12: ffffa17d4eb7fa80 > > > > > R13: 0000000000001a40 R14: 000000000000041a R15: ffffa17d40167e30 > > > > > FS: 0000000000000000(0000) GS:ffff895257380000(0000) > > > > > knlGS:0000000000000000 > > > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > > > CR2: ffffa17d40e0b000 CR3: 00000001eaeca006 CR4: 00000000001706e0 > > > > > Call Trace: > > > > > <TASK> > > > > > ? drm_fbdev_generic_helper_fb_dirty+0x207/0x330 [drm_kms_helper] > > > > > drm_fb_helper_damage_work+0x8f/0x170 [drm_kms_helper] > > > > > process_one_work+0x21f/0x430 > > > > > worker_thread+0x4e/0x3c0 > > > > > ? __pfx_worker_thread+0x10/0x10 > > > > > kthread+0xf4/0x120 > > > > > ? __pfx_kthread+0x10/0x10 > > > > > ret_from_fork+0x2c/0x50 > > > > > </TASK> > > > > > CR2: ffffa17d40e0b000 > > > > > ---[ end trace 0000000000000000 ]--- > > > > > > > > > > The indirect reason is drm_fb_helper_memory_range_to_clip() > > > > > generate damage > > > > > rectangles which partially or completely go out of the > > > > > active display area. > > > > > The second of argument 'off' is passing from the user-space, > > > > > this will lead > > > > > to the out-of-bound if it is large than (fb_height + 1) * > > > > > fb_pitches; while > > > > > DIV_ROUND_UP() may also controbute to error by 1. > > > > > > > > > > This patch will add code to restrict the damage rect > > > > > computed go beyond of > > > > > the last line of the framebuffer. > > > > > > > > > > Signed-off-by: Sui Jingfeng <suijingfeng@loongson.cn> > > > > > --- > > > > > drivers/gpu/drm/drm_fb_helper.c | 16 ++++++++++++---- > > > > > drivers/gpu/drm/drm_fbdev_generic.c | 2 +- > > > > > 2 files changed, 13 insertions(+), 5 deletions(-) > > > > > > > > > > diff --git a/drivers/gpu/drm/drm_fb_helper.c > > > > > b/drivers/gpu/drm/drm_fb_helper.c > > > > > index 64458982be40..6bb1b8b27d7a 100644 > > > > > --- a/drivers/gpu/drm/drm_fb_helper.c > > > > > +++ b/drivers/gpu/drm/drm_fb_helper.c > > > > > @@ -641,19 +641,27 @@ static void > > > > > drm_fb_helper_damage(struct drm_fb_helper *helper, u32 x, > > > > > u32 y, > > > > > static void drm_fb_helper_memory_range_to_clip(struct > > > > > fb_info *info, off_t off, size_t len, > > > > > struct drm_rect *clip) > > > > > { > > > > > + u32 line_length = info->fix.line_length; > > > > > + u32 fb_height = info->var.yres; > > > > > off_t end = off + len; > > > > > u32 x1 = 0; > > > > > - u32 y1 = off / info->fix.line_length; > > > > > + u32 y1 = off / line_length; > > > > > u32 x2 = info->var.xres; > > > > > - u32 y2 = DIV_ROUND_UP(end, info->fix.line_length); > > > > > + u32 y2 = DIV_ROUND_UP(end, line_length); > > > > > + > > > > > + /* Don't allow any of them beyond the bottom bound of > > > > > display area */ > > > > > + if (y1 > fb_height) > > > > > + y1 = fb_height; > > > > > + if (y2 > fb_height) > > > > > + y2 = fb_height; > > > > > if ((y2 - y1) == 1) { > > > > > /* > > > > > * We've only written to a single scanline. Try to reduce > > > > > * the number of horizontal pixels that need an update. > > > > > */ > > > > > - off_t bit_off = (off % info->fix.line_length) * 8; > > > > > - off_t bit_end = (end % info->fix.line_length) * 8; > > > > > + off_t bit_off = (off % line_length) * 8; > > > > > + off_t bit_end = (end % line_length) * 8; > > > > > > > > Please scratch all these changes. The current code should work > > > > as intended. Only the generic fbdev emulation uses this code and > > > > it should really be moved there at some point. > > > > > > > > > Are you meant that we should remove all these changes in > > > drivers/gpu/drm/drm_fb_helper.c ? > > > > As Daniel mentioned, there's the discussion in the other thread. I don't > > want to reopen it here. Just to summarize: I'm not convinced that this > > should be DRM code because it can be shared with other fbdev drivers. > > > > [...] > > > > > > > diff --git a/drivers/gpu/drm/drm_fbdev_generic.c > > > > > b/drivers/gpu/drm/drm_fbdev_generic.c > > > > > index 8e5148bf40bb..b057cfbba938 100644 > > > > > --- a/drivers/gpu/drm/drm_fbdev_generic.c > > > > > +++ b/drivers/gpu/drm/drm_fbdev_generic.c > > > > > @@ -94,7 +94,7 @@ static int > > > > > drm_fbdev_generic_helper_fb_probe(struct drm_fb_helper > > > > > *fb_helper, > > > > > fb_helper->buffer = buffer; > > > > > fb_helper->fb = buffer->fb; > > > > > - screen_size = buffer->gem->size; > > > > > + screen_size = sizes->surface_height * buffer->fb->pitches[0]; > > > > This has been bothering me over the weekend. And I think it's because > > what we want the screen_size to be heigth * pitch, but the mmap'ed > > memory is still at page granularity. Therefore... > > > > [...] > > > > > > > > > screen_buffer = vzalloc(screen_size); > > > > ... this line should explicitly allocate multiples of pages. Something > > like > > > > /* allocate page-size multiples for mmap */ > > vzalloc(PAGE_ALIGN(screen_size)) > > > I just thought about your instruction at here, thanks! > > But it is already page size aligned if we don't tough it. > > It is guaranteed by the GEM memory manger, > > so a previous patch tested by me, is turn out to be a extremely correct? > > We exposed a page size aligned buffer(even though it is larger than needed) > is actually for mmap ? mmap() is always page aligned, because that's the smallest size the cpu pagetables can map. So there's fundamentally always a bit of memory at the end of the buffer which logically is not part of the framebuffer memory. And somehow we need to handle that to make sure we don't overflow. -Daniel > > > > It has not been a bug so far because vzalloc() always returns full pages > > IIRC. It's still worth fixing. > > > > > Best regards > > Thomas > > > > > > > > > if (!screen_buffer) { > > > > > ret = -ENOMEM; > > > > > >
Hi, On 2023/4/27 17:34, Daniel Vetter wrote: > On Thu, Apr 20, 2023 at 02:47:24AM +0800, Sui Jingfeng wrote: >> Hi, >> >> On 2023/4/17 15:29, Thomas Zimmermann wrote: >>> Hi >>> >>> Am 14.04.23 um 12:58 schrieb Sui Jingfeng: >>>> Hi, >>>> >>>> On 2023/4/14 03:16, Thomas Zimmermann wrote: >>>>> Hi, >>>>> >>>>> thanks for the patch. This is effectively a revert of commit >>>>> 8fbc9af55de0 ("drm/fbdev-generic: Set screen size to size of GEM >>>>> buffer"). Please add a Fixes tag. >>>>> >>>>> Am 13.04.23 um 20:06 schrieb Sui Jingfeng: >>>>>> From: Sui Jingfeng <suijingfeng@loongson.cn> >>>>>> >>>>>> The crazy fbdev test of IGT may write after EOF, which lead >>>>>> to out-of-bound >>>>> Please drop 'crazy'. :) >>>> This is OK. >>>> >>>> By using the world 'crazy', >>>> >>>> I meant that the test is very good and maybe it is written by >>>> professional peoples >>>> >>>> with the guidance by experienced engineer. So that even the corner >>>> get tested. >>>> >>>> >>>>>> access for the drm drivers using fbdev-generic. For example, >>>>>> run fbdev test >>>>>> on a x86-64+ast2400 platform with 1680x1050 resolution will >>>>>> cause the linux >>>>>> kernel hang with following call trace: >>>>>> >>>>>> Oops: 0000 [#1] PREEMPT SMP PTI >>>>>> [IGT] fbdev: starting subtest eof >>>>>> Workqueue: events drm_fb_helper_damage_work [drm_kms_helper] >>>>>> [IGT] fbdev: starting subtest nullptr >>>>>> >>>>>> RIP: 0010:memcpy_erms+0xa/0x20 >>>>>> RSP: 0018:ffffa17d40167d98 EFLAGS: 00010246 >>>>>> RAX: ffffa17d4eb7fa80 RBX: ffffa17d40e0aa80 RCX: 00000000000014c0 >>>>>> RDX: 0000000000001a40 RSI: ffffa17d40e0b000 RDI: ffffa17d4eb80000 >>>>>> RBP: ffffa17d40167e20 R08: 0000000000000000 R09: ffff89522ecff8c0 >>>>>> R10: ffffa17d4e4c5000 R11: 0000000000000000 R12: ffffa17d4eb7fa80 >>>>>> R13: 0000000000001a40 R14: 000000000000041a R15: ffffa17d40167e30 >>>>>> FS: 0000000000000000(0000) GS:ffff895257380000(0000) >>>>>> knlGS:0000000000000000 >>>>>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>>>>> CR2: ffffa17d40e0b000 CR3: 00000001eaeca006 CR4: 00000000001706e0 >>>>>> Call Trace: >>>>>> <TASK> >>>>>> ? drm_fbdev_generic_helper_fb_dirty+0x207/0x330 [drm_kms_helper] >>>>>> drm_fb_helper_damage_work+0x8f/0x170 [drm_kms_helper] >>>>>> process_one_work+0x21f/0x430 >>>>>> worker_thread+0x4e/0x3c0 >>>>>> ? __pfx_worker_thread+0x10/0x10 >>>>>> kthread+0xf4/0x120 >>>>>> ? __pfx_kthread+0x10/0x10 >>>>>> ret_from_fork+0x2c/0x50 >>>>>> </TASK> >>>>>> CR2: ffffa17d40e0b000 >>>>>> ---[ end trace 0000000000000000 ]--- >>>>>> >>>>>> The indirect reason is drm_fb_helper_memory_range_to_clip() >>>>>> generate damage >>>>>> rectangles which partially or completely go out of the >>>>>> active display area. >>>>>> The second of argument 'off' is passing from the user-space, >>>>>> this will lead >>>>>> to the out-of-bound if it is large than (fb_height + 1) * >>>>>> fb_pitches; while >>>>>> DIV_ROUND_UP() may also controbute to error by 1. >>>>>> >>>>>> This patch will add code to restrict the damage rect >>>>>> computed go beyond of >>>>>> the last line of the framebuffer. >>>>>> >>>>>> Signed-off-by: Sui Jingfeng <suijingfeng@loongson.cn> >>>>>> --- >>>>>> drivers/gpu/drm/drm_fb_helper.c | 16 ++++++++++++---- >>>>>> drivers/gpu/drm/drm_fbdev_generic.c | 2 +- >>>>>> 2 files changed, 13 insertions(+), 5 deletions(-) >>>>>> >>>>>> diff --git a/drivers/gpu/drm/drm_fb_helper.c >>>>>> b/drivers/gpu/drm/drm_fb_helper.c >>>>>> index 64458982be40..6bb1b8b27d7a 100644 >>>>>> --- a/drivers/gpu/drm/drm_fb_helper.c >>>>>> +++ b/drivers/gpu/drm/drm_fb_helper.c >>>>>> @@ -641,19 +641,27 @@ static void >>>>>> drm_fb_helper_damage(struct drm_fb_helper *helper, u32 x, >>>>>> u32 y, >>>>>> static void drm_fb_helper_memory_range_to_clip(struct >>>>>> fb_info *info, off_t off, size_t len, >>>>>> struct drm_rect *clip) >>>>>> { >>>>>> + u32 line_length = info->fix.line_length; >>>>>> + u32 fb_height = info->var.yres; >>>>>> off_t end = off + len; >>>>>> u32 x1 = 0; >>>>>> - u32 y1 = off / info->fix.line_length; >>>>>> + u32 y1 = off / line_length; >>>>>> u32 x2 = info->var.xres; >>>>>> - u32 y2 = DIV_ROUND_UP(end, info->fix.line_length); >>>>>> + u32 y2 = DIV_ROUND_UP(end, line_length); >>>>>> + >>>>>> + /* Don't allow any of them beyond the bottom bound of >>>>>> display area */ >>>>>> + if (y1 > fb_height) >>>>>> + y1 = fb_height; >>>>>> + if (y2 > fb_height) >>>>>> + y2 = fb_height; >>>>>> if ((y2 - y1) == 1) { >>>>>> /* >>>>>> * We've only written to a single scanline. Try to reduce >>>>>> * the number of horizontal pixels that need an update. >>>>>> */ >>>>>> - off_t bit_off = (off % info->fix.line_length) * 8; >>>>>> - off_t bit_end = (end % info->fix.line_length) * 8; >>>>>> + off_t bit_off = (off % line_length) * 8; >>>>>> + off_t bit_end = (end % line_length) * 8; >>>>> Please scratch all these changes. The current code should work >>>>> as intended. Only the generic fbdev emulation uses this code and >>>>> it should really be moved there at some point. >>>> >>>> Are you meant that we should remove all these changes in >>>> drivers/gpu/drm/drm_fb_helper.c ? >>> As Daniel mentioned, there's the discussion in the other thread. I don't >>> want to reopen it here. Just to summarize: I'm not convinced that this >>> should be DRM code because it can be shared with other fbdev drivers. >>> >>> [...] >>> >>>>>> diff --git a/drivers/gpu/drm/drm_fbdev_generic.c >>>>>> b/drivers/gpu/drm/drm_fbdev_generic.c >>>>>> index 8e5148bf40bb..b057cfbba938 100644 >>>>>> --- a/drivers/gpu/drm/drm_fbdev_generic.c >>>>>> +++ b/drivers/gpu/drm/drm_fbdev_generic.c >>>>>> @@ -94,7 +94,7 @@ static int >>>>>> drm_fbdev_generic_helper_fb_probe(struct drm_fb_helper >>>>>> *fb_helper, >>>>>> fb_helper->buffer = buffer; >>>>>> fb_helper->fb = buffer->fb; >>>>>> - screen_size = buffer->gem->size; >>>>>> + screen_size = sizes->surface_height * buffer->fb->pitches[0]; >>> This has been bothering me over the weekend. And I think it's because >>> what we want the screen_size to be heigth * pitch, but the mmap'ed >>> memory is still at page granularity. Therefore... >>> >>> [...] >>>>>> screen_buffer = vzalloc(screen_size); >>> ... this line should explicitly allocate multiples of pages. Something >>> like >>> >>> /* allocate page-size multiples for mmap */ >>> vzalloc(PAGE_ALIGN(screen_size)) >>> >> I just thought about your instruction at here, thanks! >> >> But it is already page size aligned if we don't tough it. >> >> It is guaranteed by the GEM memory manger, >> >> so a previous patch tested by me, is turn out to be a extremely correct? >> >> We exposed a page size aligned buffer(even though it is larger than needed) >> is actually for mmap ? > mmap() is always page aligned, because that's the smallest size the cpu > pagetables can map. So there's fundamentally always a bit of memory at the > end of the buffer which logically is not part of the framebuffer memory. > And somehow we need to handle that to make sure we don't overflow. > -Daniel Yeah, buffer allocating should be page size aligned, A single page share the same caching property. fbdev test use the `smem_len` member of `fix_info` to know the true size of the shadow screen buffer. Exposing a large one actually allow the test writing to somewhere beyond the logically visible area. I need to learn more and testing more to verify if there are still risks, I'll take a look. Thanks for sharing the knowledge. >> >>> It has not been a bug so far because vzalloc() always returns full pages >>> IIRC. It's still worth fixing. >>> >>> Best regards >>> Thomas >>> >>> >>>>>> if (!screen_buffer) { >>>>>> ret = -ENOMEM;
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index 64458982be40..6bb1b8b27d7a 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -641,19 +641,27 @@ static void drm_fb_helper_damage(struct drm_fb_helper *helper, u32 x, u32 y, static void drm_fb_helper_memory_range_to_clip(struct fb_info *info, off_t off, size_t len, struct drm_rect *clip) { + u32 line_length = info->fix.line_length; + u32 fb_height = info->var.yres; off_t end = off + len; u32 x1 = 0; - u32 y1 = off / info->fix.line_length; + u32 y1 = off / line_length; u32 x2 = info->var.xres; - u32 y2 = DIV_ROUND_UP(end, info->fix.line_length); + u32 y2 = DIV_ROUND_UP(end, line_length); + + /* Don't allow any of them beyond the bottom bound of display area */ + if (y1 > fb_height) + y1 = fb_height; + if (y2 > fb_height) + y2 = fb_height; if ((y2 - y1) == 1) { /* * We've only written to a single scanline. Try to reduce * the number of horizontal pixels that need an update. */ - off_t bit_off = (off % info->fix.line_length) * 8; - off_t bit_end = (end % info->fix.line_length) * 8; + off_t bit_off = (off % line_length) * 8; + off_t bit_end = (end % line_length) * 8; x1 = bit_off / info->var.bits_per_pixel; x2 = DIV_ROUND_UP(bit_end, info->var.bits_per_pixel); diff --git a/drivers/gpu/drm/drm_fbdev_generic.c b/drivers/gpu/drm/drm_fbdev_generic.c index 8e5148bf40bb..b057cfbba938 100644 --- a/drivers/gpu/drm/drm_fbdev_generic.c +++ b/drivers/gpu/drm/drm_fbdev_generic.c @@ -94,7 +94,7 @@ static int drm_fbdev_generic_helper_fb_probe(struct drm_fb_helper *fb_helper, fb_helper->buffer = buffer; fb_helper->fb = buffer->fb; - screen_size = buffer->gem->size; + screen_size = sizes->surface_height * buffer->fb->pitches[0]; screen_buffer = vzalloc(screen_size); if (!screen_buffer) { ret = -ENOMEM;