This reverts commit 1a148af06000e545e714fe3210af3d77ff903c11.

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 Cc: stable@vger.kernel.org # v6.15+ --- drivers/gpu/drm/drm_gem_shmem_helper.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index 8ac0b1fa5287..5d1349c34afd 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -351,7 +351,7 @@ int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, dma_resv_assert_held(obj->resv);

if (drm_gem_is_imported(obj)) { - ret = dma_buf_vmap(obj->dma_buf, map); + ret = dma_buf_vmap(obj->import_attach->dmabuf, map); } else { pgprot_t prot = PAGE_KERNEL;

@@ -413,7 +413,7 @@ void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem, dma_resv_assert_held(obj->resv);

if (drm_gem_is_imported(obj)) { - dma_buf_vunmap(obj->dma_buf, map); + dma_buf_vunmap(obj->import_attach->dmabuf, map); } else { dma_resv_assert_held(shmem->base.resv);