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drm/nouveau: RCU-free the scheduler-containing nouveau_sched

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struct nouveau_sched embeds a struct drm_gpu_scheduler (base).
nouveau_sched_destroy() calls nouveau_sched_fini() (which does
drm_sched_fini(&sched->base)) and then frees the object with plain
kfree(sched).

drm_sched_fence_get_timeline_name() returns fence->sched->name, and the
scheduler fence keeps a .release callback so it is not ops-detached on
signalling.  A finished fence exported to userspace via drm_syncobj /
sync_file therefore keeps pointing at &sched->base after nouveau_sched_destroy(),
and a later get_timeline_name() -- reachable unprivileged through
SYNC_IOC_FILE_INFO -- dereferences freed memory (KASAN slab-use-after-free
read).

Per the dma-fence lifetime contract the exporter must keep the data backing a
signalled fence alive for an RCU grace period.  Free the scheduler-containing
object with kfree_rcu() instead of kfree().

Fixes: 5f03a507b2 ("drm/nouveau: implement 1:1 scheduler - entity relationship")
Cc: stable@vger.kernel.org
Signed-off-by: Jonghyuk Kim(MalHyuk) <malhyuk97@gmail.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patch.msgid.link/20260902012717.880724-1-malhyuk97@gmail.com
This commit is contained in:
Jonghyuk Kim(MalHyuk) 2026-09-02 10:27:16 +09:00 committed by Lyude Paul
parent 3359a372ef
commit f7eae6d8d7
2 changed files with 2 additions and 1 deletions
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2
drivers/gpu/drm/nouveau/nouveau_sched.c
View File

@ -517,7 +517,7 @@ nouveau_sched_destroy(struct nouveau_sched **psched)
struct nouveau_sched *sched = *psched;
nouveau_sched_fini(sched);
kfree(sched);
kfree_rcu(sched, rcu);
*psched = NULL;
}

1
drivers/gpu/drm/nouveau/nouveau_sched.h
View File

@ -98,6 +98,7 @@ void nouveau_job_free(struct nouveau_job *job);
struct nouveau_sched {
struct drm_gpu_scheduler base;
struct rcu_head rcu;
struct drm_sched_entity entity;
struct workqueue_struct *wq;
struct mutex mutex;