| Message ID | 20220302143311.2109322-1-zheyuma97@gmail.com (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Headers | show |
| Series | video: fbdev: sm712fb: Fix crash in smtcfb_write() | expand |
On 3/2/22 15:33, Zheyu Ma wrote: > When the sm712fb driver writes three bytes to the framebuffer, the > driver will crash: > > BUG: unable to handle page fault for address: ffffc90001ffffff > RIP: 0010:smtcfb_write+0x454/0x5b0 > Call Trace: > vfs_write+0x291/0xd60 > ? do_sys_openat2+0x27d/0x350 > ? __fget_light+0x54/0x340 > ksys_write+0xce/0x190 > do_syscall_64+0x43/0x90 > entry_SYSCALL_64_after_hwframe+0x44/0xae > > Fix it by removing the open-coded endianness fixup-code. > > Signed-off-by: Zheyu Ma <zheyuma97@gmail.com> Thanks... it's already in the fbdev git tree and queued up for v5.18... https://git.kernel.org/pub/scm/linux/kernel/git/deller/linux-fbdev.git/commit/?h=for-next&id=bd771cf5c4254511cc4abb88f3dab3bd58bdf8e8 Helge > --- > drivers/video/fbdev/sm712fb.c | 21 ++++----------------- > 1 file changed, 4 insertions(+), 17 deletions(-) > > diff --git a/drivers/video/fbdev/sm712fb.c b/drivers/video/fbdev/sm712fb.c > index 0dbc6bf8268a..e355089ac7d6 100644 > --- a/drivers/video/fbdev/sm712fb.c > +++ b/drivers/video/fbdev/sm712fb.c > @@ -1130,7 +1130,7 @@ static ssize_t smtcfb_write(struct fb_info *info, const char __user *buf, > count = total_size - p; > } > > - buffer = kmalloc((count > PAGE_SIZE) ? PAGE_SIZE : count, GFP_KERNEL); > + buffer = kmalloc(PAGE_SIZE, GFP_KERNEL); > if (!buffer) > return -ENOMEM; > > @@ -1148,24 +1148,11 @@ static ssize_t smtcfb_write(struct fb_info *info, const char __user *buf, > break; > } > > - for (i = c >> 2; i--;) { > - fb_writel(big_swap(*src), dst++); > + for (i = (c + 3) >> 2; i--;) { > + fb_writel(big_swap(*src), dst); > + dst++; > src++; > } > - if (c & 3) { > - u8 *src8 = (u8 *)src; > - u8 __iomem *dst8 = (u8 __iomem *)dst; > - > - for (i = c & 3; i--;) { > - if (i & 1) { > - fb_writeb(*src8++, ++dst8); > - } else { > - fb_writeb(*src8++, --dst8); > - dst8 += 2; > - } > - } > - dst = (u32 __iomem *)dst8; > - } > > *ppos += c; > buf += c;
Hi, On Thu, Mar 3, 2022 at 12:49 AM Helge Deller <deller@gmx.de> wrote: > > On 3/2/22 15:33, Zheyu Ma wrote: > > When the sm712fb driver writes three bytes to the framebuffer, the > > driver will crash: > > > > BUG: unable to handle page fault for address: ffffc90001ffffff > > RIP: 0010:smtcfb_write+0x454/0x5b0 > > Call Trace: > > vfs_write+0x291/0xd60 > > ? do_sys_openat2+0x27d/0x350 > > ? __fget_light+0x54/0x340 > > ksys_write+0xce/0x190 > > do_syscall_64+0x43/0x90 > > entry_SYSCALL_64_after_hwframe+0x44/0xae > > > > Fix it by removing the open-coded endianness fixup-code. > > > > Signed-off-by: Zheyu Ma <zheyuma97@gmail.com> > > Thanks... it's already in the fbdev git tree and queued up for v5.18... > https://git.kernel.org/pub/scm/linux/kernel/git/deller/linux-fbdev.git/commit/?h=for-next&id=bd771cf5c4254511cc4abb88f3dab3bd58bdf8e8 This patch fixes the crash in smtcfb_read(), but there is a similar bug in smtcfb_write(), and I mocked up your patch a wrote a new patch for it. So we should fix two bugs with two patches. Regards, Zheyu Ma
On 3/3/22 02:34, Zheyu Ma wrote: > Hi, > > On Thu, Mar 3, 2022 at 12:49 AM Helge Deller <deller@gmx.de> wrote: >> >> On 3/2/22 15:33, Zheyu Ma wrote: >>> When the sm712fb driver writes three bytes to the framebuffer, the >>> driver will crash: >>> >>> BUG: unable to handle page fault for address: ffffc90001ffffff >>> RIP: 0010:smtcfb_write+0x454/0x5b0 >>> Call Trace: >>> vfs_write+0x291/0xd60 >>> ? do_sys_openat2+0x27d/0x350 >>> ? __fget_light+0x54/0x340 >>> ksys_write+0xce/0x190 >>> do_syscall_64+0x43/0x90 >>> entry_SYSCALL_64_after_hwframe+0x44/0xae >>> >>> Fix it by removing the open-coded endianness fixup-code. >>> >>> Signed-off-by: Zheyu Ma <zheyuma97@gmail.com> >> >> Thanks... it's already in the fbdev git tree and queued up for v5.18... >> https://git.kernel.org/pub/scm/linux/kernel/git/deller/linux-fbdev.git/commit/?h=for-next&id=bd771cf5c4254511cc4abb88f3dab3bd58bdf8e8 > > This patch fixes the crash in smtcfb_read(), but there is a similar > bug in smtcfb_write(), and I mocked up your patch a wrote a new patch > for it. > So we should fix two bugs with two patches. Right, I missed the read() code. I applied your patch now to the fbdev for-next git tree. Thanks! Helge > > Regards, > Zheyu Ma
diff --git a/drivers/video/fbdev/sm712fb.c b/drivers/video/fbdev/sm712fb.c index 0dbc6bf8268a..e355089ac7d6 100644 --- a/drivers/video/fbdev/sm712fb.c +++ b/drivers/video/fbdev/sm712fb.c @@ -1130,7 +1130,7 @@ static ssize_t smtcfb_write(struct fb_info *info, const char __user *buf, count = total_size - p; } - buffer = kmalloc((count > PAGE_SIZE) ? PAGE_SIZE : count, GFP_KERNEL); + buffer = kmalloc(PAGE_SIZE, GFP_KERNEL); if (!buffer) return -ENOMEM; @@ -1148,24 +1148,11 @@ static ssize_t smtcfb_write(struct fb_info *info, const char __user *buf, break; } - for (i = c >> 2; i--;) { - fb_writel(big_swap(*src), dst++); + for (i = (c + 3) >> 2; i--;) { + fb_writel(big_swap(*src), dst); + dst++; src++; } - if (c & 3) { - u8 *src8 = (u8 *)src; - u8 __iomem *dst8 = (u8 __iomem *)dst; - - for (i = c & 3; i--;) { - if (i & 1) { - fb_writeb(*src8++, ++dst8); - } else { - fb_writeb(*src8++, --dst8); - dst8 += 2; - } - } - dst = (u32 __iomem *)dst8; - } *ppos += c; buf += c;
When the sm712fb driver writes three bytes to the framebuffer, the driver will crash: BUG: unable to handle page fault for address: ffffc90001ffffff RIP: 0010:smtcfb_write+0x454/0x5b0 Call Trace: vfs_write+0x291/0xd60 ? do_sys_openat2+0x27d/0x350 ? __fget_light+0x54/0x340 ksys_write+0xce/0x190 do_syscall_64+0x43/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae Fix it by removing the open-coded endianness fixup-code. Signed-off-by: Zheyu Ma <zheyuma97@gmail.com> --- drivers/video/fbdev/sm712fb.c | 21 ++++----------------- 1 file changed, 4 insertions(+), 17 deletions(-)