Revert "drm/etnaviv: Use dma_buf from GEM object instance"

This reverts commit e91eb3ae41.

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 5307dce878 ("drm/gem: Acquire references on
GEM handles for framebuffers") and commit f6bfc9afc7 ("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.

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>
Link: https://lore.kernel.org/r/20250715155934.150656-4-tzimmermann@suse.de
This commit is contained in:
Thomas Zimmermann 2025-07-15 17:58:13 +02:00
parent 1e9d2aed7c
commit bb7f4972a6

View File

@ -65,7 +65,7 @@ static void etnaviv_gem_prime_release(struct etnaviv_gem_object *etnaviv_obj)
struct iosys_map map = IOSYS_MAP_INIT_VADDR(etnaviv_obj->vaddr);
if (etnaviv_obj->vaddr)
dma_buf_vunmap_unlocked(etnaviv_obj->base.dma_buf, &map);
dma_buf_vunmap_unlocked(etnaviv_obj->base.import_attach->dmabuf, &map);
/* Don't drop the pages for imported dmabuf, as they are not
* ours, just free the array we allocated:
@ -82,7 +82,7 @@ static void *etnaviv_gem_prime_vmap_impl(struct etnaviv_gem_object *etnaviv_obj)
lockdep_assert_held(&etnaviv_obj->lock);
ret = dma_buf_vmap(etnaviv_obj->base.dma_buf, &map);
ret = dma_buf_vmap(etnaviv_obj->base.import_attach->dmabuf, &map);
if (ret)
return NULL;
return map.vaddr;