CVE-2026-98243

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

dma-buf/dma-fence: fix checking signaling bit for timeline and driver name v3

The patch "dma-buf: dma-fence: Fix potential NULL pointer dereference"

changed the check to test for the ops pointer instead of the signaled

bit to avoid a potential NULL dereference when the ops pointer has been

cleared.

The problem is now that the ops pointer is cleared only when neither the

release nor the wait callback is implemented and this isn't true for a lot

of dma_fence implementations yet. So those implementations lost the RCU

protection after signaling of the returned string resulting in potential

use after free.

Add the signaling check additional to the ops pointer check so that we

have both the protection against NULL dereference as well as the RCU

protection after signaling for the returned string.

v2: improve comments to note RCU protection and explain why we check

both signaling state and ops pointer

v3: some comment

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References