Bug 2393157 (CVE-2025-38703)

Summary: CVE-2025-38703 kernel: drm/xe: Make dma-fences compliant with the safe access rules
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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Description OSIDB Bzimport 2025-09-04 16:01:34 UTC 
In the Linux kernel, the following vulnerability has been resolved:

drm/xe: Make dma-fences compliant with the safe access rules

Xe can free some of the data pointed to by the dma-fences it exports. Most
notably the timeline name can get freed if userspace closes the associated
submit queue. At the same time the fence could have been exported to a
third party (for example a sync_fence fd) which will then cause an use-
after-free on subsequent access.

To make this safe we need to make the driver compliant with the newly
documented dma-fence rules. Driver has to ensure a RCU grace period
between signalling a fence and freeing any data pointed to by said fence.

For the timeline name we simply make the queue be freed via kfree_rcu and
for the shared lock associated with multiple queues we add a RCU grace
period before freeing the per GT structure holding the lock.
Comment 1 Jon Moroney 2025-09-04 20:07:56 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025090453-CVE-2025-38703-2f5c@gregkh/T