Am 08.07.21 um 12:09 schrieb Pavel Skripkin:
On Thu, 8 Jul 2021 11:37:01 +0300
Pavel Skripkin <paskripkin@xxxxxxxxx> wrote:
On Thu, 8 Jul 2021 08:49:48 +0200
Christian König <christian.koenig@xxxxxxx> wrote:
Am 07.07.21 um 20:51 schrieb Pavel Skripkin:
My local syzbot instance hit GPF in ttm_bo_release().
Unfortunately, syzbot didn't produce a reproducer for this, but I
found out possible scenario:
drm_gem_vram_create() <-- drm_gem_vram_object kzalloced
(bo embedded in this object)
ttm_bo_init()
ttm_bo_init_reserved()
ttm_resource_alloc()
man->func->alloc() <-- allocation failure
ttm_bo_put()
ttm_bo_release()
ttm_mem_io_free() <-- bo->resource == NULL passed
as second argument
*GPF*
So, I've added check in ttm_bo_release() to avoid passing
NULL as second argument to ttm_mem_io_free().
Hi, Christian!
Thank you for quick feedback :)
There is another ocassion of this a bit down before we call
ttm_bo_move_to_lru_tail() apart from that good catch.
Did you mean, that ttm_bo_move_to_lru_tail() should have NULL check
too?
Yes, exactly that.
I checked it's realization, and, I think, NULL check is necessary
there, since mem pointer is dereferenced w/o any checking
But I'm wondering if we should make the functions NULL save instead
of the external check.
I tried to find more possible scenarios of GPF in ttm_bo_release(),
but I didn't find one. But, yes, moving NULL check inside
ttm_mem_io_free() is more general approach and it will defend this
function from GPFs in the future.
With regards,
Pavel Skripkin
I misclicked and sent this email to Christian privately :(
Added all thread participants back, sorry.
No problem.
Do you want to update your patch or should I take care of this?
Thanks,
Christian.
With regards,
Pavel Skripkin
