On Tue, 2024-12-10 at 15:41 -0500, Sasha Levin wrote:

This is a note to let you know that I've just added the patch titled

drm/sched: memset() 'job' in drm_sched_job_init()

to the 6.12-stable tree which can be found at:     http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is:      drm-sched-memset-job-in-drm_sched_job_init.patch and it can be found in the queue-6.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

Hi,

you can add it, it does improve things a bit.

But I'd like to use this opportunity to understand by what criteria you found and selected this patch? Stable was not on CC, neither does the patch contain a Fixes tag.

Regards, P.

commit d0a6c893de0172427064e39be400a23b0ba5ffec Author: Philipp Stanner pstanner@redhat.com Date:   Mon Oct 21 12:50:28 2024 +0200

drm/sched: memset() 'job' in drm_sched_job_init()         [ Upstream commit 2320c9e6a768d135c7b0039995182bb1a4e4fd22 ]         drm_sched_job_init() has no control over how users allocate struct     drm_sched_job. Unfortunately, the function can also not set some struct     members such as job->sched.         This could theoretically lead to UB by users dereferencing the struct's     pointer members too early.         It is easier to debug such issues if these pointers are initialized to     NULL, so dereferencing them causes a NULL pointer exception.     Accordingly, drm_sched_entity_init() does precisely that and initializes     its struct with memset().         Initialize parameter "job" to 0 in drm_sched_job_init().         Signed-off-by: Philipp Stanner pstanner@redhat.com     Link: https://patchwork.freedesktop.org/patch/msgid/20241021105028.19794-2-pstanne...     Reviewed-by: Christian König christian.koenig@amd.com     Signed-off-by: Sasha Levin sashal@kernel.org

diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c index e97c6c60bc96e..416590ea0dc3d 100644 --- a/drivers/gpu/drm/scheduler/sched_main.c +++ b/drivers/gpu/drm/scheduler/sched_main.c @@ -803,6 +803,14 @@ int drm_sched_job_init(struct drm_sched_job *job,   return -EINVAL;   }

• /*

• * We don't know for sure how the user has allocated. Thus,
  

zero the

• * struct so that unallowed (i.e., too early) usage of
  

pointers that

• * this function does not set is guaranteed to lead to a
  

NULL pointer

• * exception instead of UB.
  

• */
  

• memset(job, 0, sizeof(*job));

job->entity = entity;   job->credits = credits;   job->s_fence = drm_sched_fence_alloc(entity, owner);