On Fri, Sep 03, 2021 at 02:05:54PM +0200, Boris Brezillon wrote:
drm_sched_job_cleanup() will pass an uninitialized fence to drm_sched_fence_free(), which will cause to_drm_sched_fence() to return a NULL fence object, causing a NULL pointer deref when this NULL object is passed to kmem_cache_free().
Let's create a new drm_sched_fence_free() function that takes a drm_sched_fence pointer and suffix the old function with _rcu. While at it, complain if drm_sched_fence_free() is passed an initialized fence or if drm_sched_fence_free_rcu() is passed an uninitialized fence.
Fixes: dbe48d030b28 ("drm/sched: Split drm_sched_job_init") Signed-off-by: Boris Brezillon boris.brezillon@collabora.com
Found while debugging another issue in panfrost causing a failure in the submit ioctl and exercising the error path (path that calls drm_sched_job_cleanup() on an unarmed job).
Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch
I already provided an irc r-b, just here for the record too. -Daniel
drivers/gpu/drm/scheduler/sched_fence.c | 29 ++++++++++++++++--------- drivers/gpu/drm/scheduler/sched_main.c | 2 +- include/drm/gpu_scheduler.h | 2 +- 3 files changed, 21 insertions(+), 12 deletions(-)
diff --git a/drivers/gpu/drm/scheduler/sched_fence.c b/drivers/gpu/drm/scheduler/sched_fence.c index db3fd1303fc4..7fd869520ef2 100644 --- a/drivers/gpu/drm/scheduler/sched_fence.c +++ b/drivers/gpu/drm/scheduler/sched_fence.c @@ -69,19 +69,28 @@ static const char *drm_sched_fence_get_timeline_name(struct dma_fence *f) return (const char *)fence->sched->name; }
-/**
- drm_sched_fence_free - free up the fence memory
- @rcu: RCU callback head
- Free up the fence memory after the RCU grace period.
- */
-void drm_sched_fence_free(struct rcu_head *rcu) +static void drm_sched_fence_free_rcu(struct rcu_head *rcu) { struct dma_fence *f = container_of(rcu, struct dma_fence, rcu); struct drm_sched_fence *fence = to_drm_sched_fence(f);
- kmem_cache_free(sched_fence_slab, fence);
- if (!WARN_ON_ONCE(!fence))
kmem_cache_free(sched_fence_slab, fence);+}
+/**
- drm_sched_fence_free - free up an uninitialized fence
- @fence: fence to free
- Free up the fence memory. Should only be used if drm_sched_fence_init()
- has not been called yet.
- */
+void drm_sched_fence_free(struct drm_sched_fence *fence) +{
- /* This function should not be called if the fence has been initialized. */
- if (!WARN_ON_ONCE(fence->sched))
kmem_cache_free(sched_fence_slab, fence);}
/** @@ -97,7 +106,7 @@ static void drm_sched_fence_release_scheduled(struct dma_fence *f) struct drm_sched_fence *fence = to_drm_sched_fence(f);
dma_fence_put(fence->parent);
- call_rcu(&fence->finished.rcu, drm_sched_fence_free);
- call_rcu(&fence->finished.rcu, drm_sched_fence_free_rcu);
}
/** diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c index fbbd3b03902f..6987d412a946 100644 --- a/drivers/gpu/drm/scheduler/sched_main.c +++ b/drivers/gpu/drm/scheduler/sched_main.c @@ -750,7 +750,7 @@ void drm_sched_job_cleanup(struct drm_sched_job *job) dma_fence_put(&job->s_fence->finished); } else { /* aborted job before committing to run it */
drm_sched_fence_free(&job->s_fence->finished.rcu);
drm_sched_fence_free(job->s_fence);}
job->s_fence = NULL;
diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h index 7f77a455722c..f011e4c407f2 100644 --- a/include/drm/gpu_scheduler.h +++ b/include/drm/gpu_scheduler.h @@ -509,7 +509,7 @@ struct drm_sched_fence *drm_sched_fence_alloc( struct drm_sched_entity *s_entity, void *owner); void drm_sched_fence_init(struct drm_sched_fence *fence, struct drm_sched_entity *entity); -void drm_sched_fence_free(struct rcu_head *rcu); +void drm_sched_fence_free(struct drm_sched_fence *fence);
void drm_sched_fence_scheduled(struct drm_sched_fence *fence); void drm_sched_fence_finished(struct drm_sched_fence *fence); -- 2.31.1