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Subject[PATCH v18 22/26] drm/shmem-helper: Don't free refcounted GEM
Date
Don't free refcounted shmem object to prevent use-after-free bug that
is worse than a memory leak.

Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
---
drivers/gpu/drm/drm_gem_shmem_helper.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index 6dd087f19ea3..4253c367dc07 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -203,9 +203,10 @@ void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem)
if (obj->import_attach)
drm_prime_gem_destroy(obj, shmem->sgt);

- drm_WARN_ON(obj->dev, refcount_read(&shmem->vmap_use_count));
- drm_WARN_ON(obj->dev, refcount_read(&shmem->pages_use_count));
- drm_WARN_ON(obj->dev, refcount_read(&shmem->pages_pin_count));
+ if (drm_WARN_ON(obj->dev, refcount_read(&shmem->vmap_use_count)) ||
+ drm_WARN_ON(obj->dev, refcount_read(&shmem->pages_use_count)) ||
+ drm_WARN_ON(obj->dev, refcount_read(&shmem->pages_pin_count)))
+ return;

drm_gem_object_release(obj);
kfree(shmem);
--
2.41.0
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