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Commit e1fc12c5 authored by Michel Dänzer's avatar Michel Dänzer Committed by Alex Deucher
Browse files

drm/ttm: Always and only destroy bo->ttm_resv in ttm_bo_release_list 



Fixes a use-after-free due to a race condition in
ttm_bo_cleanup_refs_and_unlock, which allows one task to reserve a BO
and destroy its ttm_resv while another task is waiting for it to signal
in reservation_object_wait_timeout_rcu.

v2:
* Always initialize bo->ttm_resv in ttm_bo_init_reserved
 (Christian König)

Fixes: 0d2bd2ae "drm/ttm: fix memory leak while individualizing BOs"
Reviewed-by: Chunming Zhou <david1.zhou@amd.com> # v1
Reviewed-by: default avatarChristian König <christian.koenig@amd.com>
Signed-off-by: default avatarMichel Dänzer <michel.daenzer@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent 37c5f2c9

drivers/gpu/drm/ttm/ttm_bo.c

+4 −12
Original line number Diff line number Diff line
@@ -150,7 +150,6 @@ static void ttm_bo_release_list(struct kref *list_kref) 
	ttm_tt_destroy(bo->ttm);

	atomic_dec(&bo->glob->bo_count);

	dma_fence_put(bo->moving);

	if (bo->resv == &bo->ttm_resv)

	reservation_object_fini(&bo->ttm_resv);

	mutex_destroy(&bo->wu_mutex);

	if (bo->destroy)
@@ -402,14 +401,11 @@ static int ttm_bo_individualize_resv(struct ttm_buffer_object *bo) 
	if (bo->resv == &bo->ttm_resv)

		return 0;



	reservation_object_init(&bo->ttm_resv);

	BUG_ON(!reservation_object_trylock(&bo->ttm_resv));



	r = reservation_object_copy_fences(&bo->ttm_resv, bo->resv);

	if (r) {

	if (r)

		reservation_object_unlock(&bo->ttm_resv);

		reservation_object_fini(&bo->ttm_resv);

	}



	return r;

}
@@ -457,10 +453,8 @@ static void ttm_bo_cleanup_refs_or_queue(struct ttm_buffer_object *bo) 
		if (reservation_object_test_signaled_rcu(&bo->ttm_resv, true)) {

			ttm_bo_del_from_lru(bo);

			spin_unlock(&glob->lru_lock);

			if (bo->resv != &bo->ttm_resv) {

			if (bo->resv != &bo->ttm_resv)

				reservation_object_unlock(&bo->ttm_resv);

				reservation_object_fini(&bo->ttm_resv);

			}



			ttm_bo_cleanup_memtype_use(bo);

			return;
@@ -560,8 +554,6 @@ static int ttm_bo_cleanup_refs_and_unlock(struct ttm_buffer_object *bo, 
	}



	ttm_bo_del_from_lru(bo);

	if (!list_empty(&bo->ddestroy) && (bo->resv != &bo->ttm_resv))

		reservation_object_fini(&bo->ttm_resv);

	list_del_init(&bo->ddestroy);

	kref_put(&bo->list_kref, ttm_bo_ref_bug);
@@ -1210,8 +1202,8 @@ int ttm_bo_init_reserved(struct ttm_bo_device *bdev, 
		lockdep_assert_held(&bo->resv->lock.base);

	} else {

		bo->resv = &bo->ttm_resv;

		reservation_object_init(&bo->ttm_resv);

	}

	reservation_object_init(&bo->ttm_resv);

	atomic_inc(&bo->glob->bo_count);

	drm_vma_node_reset(&bo->vma_node);

	bo->priority = 0;