| Message ID | 1426252913-5181-1-git-send-email-mika.kuoppala@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 03/13/2015 01:21 PM, Mika Kuoppala wrote: > vmap_batch() calculates amount of needed pages for the mapping > we are going to create. And it uses this page count as an > argument for the for_each_sg_pages() macro. The macro takes the number > of sg list entities as an argument, not the page count. So we ended > up iterating through all the pages on the mapped object, corrupting > memory past the smaller pages[] array. > > Fix this by bailing out when we have enough pages. > > Cc: Chris Wilson <chris@chris-wilson.co.uk> > Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com> > --- > drivers/gpu/drm/i915/i915_cmd_parser.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/i915_cmd_parser.c b/drivers/gpu/drm/i915/i915_cmd_parser.c > index 9a6da35..61ae8ff 100644 > --- a/drivers/gpu/drm/i915/i915_cmd_parser.c > +++ b/drivers/gpu/drm/i915/i915_cmd_parser.c > @@ -836,8 +836,11 @@ static u32 *vmap_batch(struct drm_i915_gem_object *obj, > } > > i = 0; > - for_each_sg_page(obj->pages->sgl, &sg_iter, npages, first_page) > + for_each_sg_page(obj->pages->sgl, &sg_iter, obj->pages->nents, first_page) { > pages[i++] = sg_page_iter_page(&sg_iter); > + if (i == npages) > + break; > + } Are you sure this manual check is needed now that you fixed for_each_sg_page? Pages array looks pessimistically big enough so I don't see that memory was getting overwritten. It looks more like our sg table was not properly terminated which made for_each_sg_page go into random memory and return random page pointers. Regards, Tvrtko
On Fri, Mar 13, 2015 at 03:21:53PM +0200, Mika Kuoppala wrote: > vmap_batch() calculates amount of needed pages for the mapping > we are going to create. And it uses this page count as an > argument for the for_each_sg_pages() macro. The macro takes the number > of sg list entities as an argument, not the page count. So we ended > up iterating through all the pages on the mapped object, corrupting > memory past the smaller pages[] array. > > Fix this by bailing out when we have enough pages. > > Cc: Chris Wilson <chris@chris-wilson.co.uk> > Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Can I ask for a st_for_each_page(&obj->pages, &sg_iter, n)? That would simplify all of our users, and stop me from making the same mistake again. -Chris
On Fri, Mar 13, 2015 at 02:05:46PM +0000, Chris Wilson wrote: > On Fri, Mar 13, 2015 at 03:21:53PM +0200, Mika Kuoppala wrote: > > vmap_batch() calculates amount of needed pages for the mapping > > we are going to create. And it uses this page count as an > > argument for the for_each_sg_pages() macro. The macro takes the number > > of sg list entities as an argument, not the page count. So we ended > > up iterating through all the pages on the mapped object, corrupting > > memory past the smaller pages[] array. > > > > Fix this by bailing out when we have enough pages. Reference to the commit which has introduced this regression is missing, I've added that. Also for next time around pls cc everyone on that patch, especially also reviewers. > > > > Cc: Chris Wilson <chris@chris-wilson.co.uk> > > Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com> > Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Queued for -next, thanks for the patch. -Daniel
Tested-By: PRC QA PRTS (Patch Regression Test System Contact: shuang.he@intel.com)
Task id: 5947
-------------------------------------Summary-------------------------------------
Platform Delta drm-intel-nightly Series Applied
PNV 276/276 276/276
ILK 303/303 303/303
SNB 279/279 279/279
IVB 343/343 343/343
BYT 287/287 287/287
HSW 363/363 363/363
BDW 308/308 308/308
-------------------------------------Detailed-------------------------------------
Platform Test drm-intel-nightly Series Applied
Note: You need to pay more attention to line start with '*'
diff --git a/drivers/gpu/drm/i915/i915_cmd_parser.c b/drivers/gpu/drm/i915/i915_cmd_parser.c index 9a6da35..61ae8ff 100644 --- a/drivers/gpu/drm/i915/i915_cmd_parser.c +++ b/drivers/gpu/drm/i915/i915_cmd_parser.c @@ -836,8 +836,11 @@ static u32 *vmap_batch(struct drm_i915_gem_object *obj, } i = 0; - for_each_sg_page(obj->pages->sgl, &sg_iter, npages, first_page) + for_each_sg_page(obj->pages->sgl, &sg_iter, obj->pages->nents, first_page) { pages[i++] = sg_page_iter_page(&sg_iter); + if (i == npages) + break; + } addr = vmap(pages, i, 0, PAGE_KERNEL); if (addr == NULL) {
vmap_batch() calculates amount of needed pages for the mapping we are going to create. And it uses this page count as an argument for the for_each_sg_pages() macro. The macro takes the number of sg list entities as an argument, not the page count. So we ended up iterating through all the pages on the mapped object, corrupting memory past the smaller pages[] array. Fix this by bailing out when we have enough pages. Cc: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com> --- drivers/gpu/drm/i915/i915_cmd_parser.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)