CVE-2025-38669Revert "drm/gem-shmem: Use dma_buf from GEM object instance"

Official description

In the Linux kernel, the following vulnerability has been resolved: Revert "drm/gem-shmem: Use dma_buf from GEM object instance" 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

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/291a77604858a8b47cf6640a12b76e97f99e00ed
• https://git.kernel.org/stable/c/6d496e9569983a0d7a05be6661126d0702cf94f7