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

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-08-22 · updated 2026-06-17
Weakness: CWE-476

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 products

Linux kernel: from 6.15 before 6.15.9; 6.16-rc1, 6.16-rc2, 6.16-rc3, 6.16-rc4, 6.16-rc5, 6.16-rc6 (+1) — fixed in 6.15.9

How to fix

Upgrade to a fixed version: Linux kernel 6.15.9. Check the vendor advisory for mitigations.

References

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