Bug 2373404 (CVE-2022-49935)

Summary:	CVE-2022-49935 kernel: dma-buf/dma-resv: check if the new fence is really later
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	dfreiber, drow, jburrell, vkumar
Target Milestone:	---	Keywords:	Security
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Hardware:	All
OS:	Linux
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
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Description OSIDB Bzimport 2025-06-18 11:01:33 UTC

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

dma-buf/dma-resv: check if the new fence is really later

Previously when we added a fence to a dma_resv object we always
assumed the the newer than all the existing fences.

With Jason's work to add an UAPI to explicit export/import that's not
necessary the case any more. So without this check we would allow
userspace to force the kernel into an use after free error.

Since the change is very small and defensive it's probably a good
idea to backport this to stable kernels as well just in case others
are using the dma_resv object in the same way.

Comment 1 Avinash Hanwate 2025-06-20 12:35:22 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025061847-CVE-2022-49935-bf21@gregkh/T