From: Thomas Zimmermann Date: Tue, 15 Jul 2025 15:58:17 +0000 (+0200) Subject: Revert "drm/gem-dma: Use dma_buf from GEM object instance" X-Git-Tag: v6.16~16^2^2~3 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=1918e79be908b8a2c8757640289bc196c14d928a;p=thirdparty%2Fkernel%2Flinux.git Revert "drm/gem-dma: Use dma_buf from GEM object instance" This reverts commit e8afa1557f4f963c9a511bd2c6074a941c308685. 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 Reviewed-by: Simona Vetter Acked-by: Christian König Acked-by: Zack Rusin Cc: # v6.15+ Link: https://lore.kernel.org/r/20250715155934.150656-8-tzimmermann@suse.de --- diff --git a/drivers/gpu/drm/drm_gem_dma_helper.c b/drivers/gpu/drm/drm_gem_dma_helper.c index b7f033d4352a3..4f0320df858f8 100644 --- a/drivers/gpu/drm/drm_gem_dma_helper.c +++ b/drivers/gpu/drm/drm_gem_dma_helper.c @@ -230,7 +230,7 @@ void drm_gem_dma_free(struct drm_gem_dma_object *dma_obj) if (drm_gem_is_imported(gem_obj)) { if (dma_obj->vaddr) - dma_buf_vunmap_unlocked(gem_obj->dma_buf, &map); + dma_buf_vunmap_unlocked(gem_obj->import_attach->dmabuf, &map); drm_prime_gem_destroy(gem_obj, dma_obj->sgt); } else if (dma_obj->vaddr) { if (dma_obj->map_noncoherent)