diff options
| author | Thomas Zimmermann <tzimmermann@suse.de> | 2025-07-15 17:58:14 +0200 |
|---|---|---|
| committer | Thomas Zimmermann <tzimmermann@suse.de> | 2025-07-17 12:26:19 +0200 |
| commit | fb4ef4a52b79a22ad382bfe77332642d02aef773 (patch) | |
| tree | b073695a93328b00e916247e8af2d8e959f59073 | |
| parent | bb7f4972a6ff9a537b87e1b0ecf0e561f2761dd3 (diff) | |
Revert "drm/prime: Use dma_buf from GEM object instance"
This reverts commit f83a9b8c7fd0557b0c50784bfdc1bbe9140c9bf8.
The dma_buf field in struct drm_gem_object is not stable over the
object instance's lifetime. The field becomes NULL when user space
releases the final GEM handle on the buffer object. This resulted
in a NULL-pointer deref.
Workarounds in commit 5307dce878d4 ("drm/gem: Acquire references on
GEM handles for framebuffers") and commit f6bfc9afc751 ("drm/framebuffer:
Acquire internal references on GEM handles") only solved the problem
partially. They especially don't work for buffer objects without a DRM
framebuffer associated.
Hence, this revert to going back to using .import_attach->dmabuf.
v3:
- cc stable
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Simona Vetter <simona.vetter@ffwll.ch>
Acked-by: Christian König <christian.koenig@amd.com>
Acked-by: Zack Rusin <zack.rusin@broadcom.com>
Cc: <stable@vger.kernel.org> # v6.15+
Link: https://lore.kernel.org/r/20250715155934.150656-5-tzimmermann@suse.de
| -rw-r--r-- | drivers/gpu/drm/drm_prime.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c index d828502268b8..a0a5d725eab0 100644 --- a/drivers/gpu/drm/drm_prime.c +++ b/drivers/gpu/drm/drm_prime.c @@ -453,7 +453,13 @@ struct dma_buf *drm_gem_prime_handle_to_dmabuf(struct drm_device *dev, } mutex_lock(&dev->object_name_lock); - /* re-export the original imported/exported object */ + /* re-export the original imported object */ + if (obj->import_attach) { + dmabuf = obj->import_attach->dmabuf; + get_dma_buf(dmabuf); + goto out_have_obj; + } + if (obj->dma_buf) { get_dma_buf(obj->dma_buf); dmabuf = obj->dma_buf; |