Commit bb7f4972 authored by Thomas Zimmermann's avatar Thomas Zimmermann
Browse files

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



This reverts commit e91eb3ae.

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 5307dce8 ("drm/gem: Acquire references on
GEM handles for framebuffers") and commit f6bfc9af ("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: default avatarThomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: default avatarSimona Vetter <simona.vetter@ffwll.ch>
Acked-by: default avatarChristian König <christian.koenig@amd.com>
Acked-by: default avatarZack Rusin <zack.rusin@broadcom.com>
Link: https://lore.kernel.org/r/20250715155934.150656-4-tzimmermann@suse.de
parent 1e9d2aed

drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c

+2 −2
Original line number Diff line number Diff line
@@ -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;