Eric Lee / smarc-fsl-linux-kernel

Download as
Browse Code ยป

Commit 8490d6a7e0a0a6fab5c2d82d57a3937306660864

Authored by Steve Cohen
Committed by Daniel Vetter
1 parent 900ab59e26

drm: hold gem reference until object is no longer accessed 

A use-after-free in drm_gem_open_ioctl can happen if the
GEM object handle is closed between the idr lookup and
retrieving the size from said object since a local reference
is not being held at that point. Hold the local reference
while the object can still be accessed to fix this and
plug the potential security hole.

Signed-off-by: Steve Cohen <cohens@codeaurora.org>
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/1595284250-31580-1-git-send-email-cohens@codeaurora.org

Showing 1 changed file with 4 additions and 6 deletions Side-by-side Diff

drivers/gpu/drm/drm_gem.c
Diff comments   View file @ 8490d6a
... ... @@ -871,9 +871,6 @@
871 871 * @file_priv: drm file-private structure
872 872 *
873 873 * Open an object using the global name, returning a handle and the size.
874   - *
875   - * This handle (of course) holds a reference to the object, so the object
876   - * will not go away until the handle is deleted.
877 874 */
878 875 int
879 876 drm_gem_open_ioctl(struct drm_device *dev, void *data,
880 877  
881 878  
... ... @@ -898,14 +895,15 @@
898 895  
899 896 /* drm_gem_handle_create_tail unlocks dev->object_name_lock. */
900 897 ret = drm_gem_handle_create_tail(file_priv, obj, &handle);
901   - drm_gem_object_put_unlocked(obj);
902 898 if (ret)
903   - return ret;
  899 + goto err;
904 900  
905 901 args->handle = handle;
906 902 args->size = obj->size;
907 903  
908   - return 0;
  904 +err:
  905 + drm_gem_object_put_unlocked(obj);
  906 + return ret;
909 907 }
910 908  
911 909 /**