Bug 2390376 (CVE-2025-38673)

Summary: CVE-2025-38673 kernel: Revert "drm/gem-framebuffer: Use dma_buf from GEM object instance"
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedKeywords: Security
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OS: Linux   
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Description OSIDB Bzimport 2025-08-22 17:03:37 UTC
In the Linux kernel, the following vulnerability has been resolved:

Revert "drm/gem-framebuffer: Use dma_buf from GEM object instance"

This reverts commit cce16fcd7446dcff7480cd9d2b6417075ed81065.

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