From d4c16733e7960aa50d6d3bc4a03ee1578baaa47b Mon Sep 17 00:00:00 2001 From: Boris Brezillon Date: Fri, 3 Sep 2021 14:05:54 +0200 Subject: [PATCH] drm/sched: Fix drm_sched_fence_free() so it can be passed an uninitialized fence 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 Reviewed-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20210903120554.444101-1-boris.brezillon@collabora.com --- 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);