In the Linux kernel, the following vulnerability has been resolved:
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
CVSS Details
- CVSS 3.1 Base Score: 5.5
- CVSS 3.1 Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
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