Bug 2532031 (CVE-2026-80955)

Summary: CVE-2026-80955 kernel: dm-pcache: fix use-after-free and invalid seg operations in kset_replay()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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Doc Text:
A flaw was found in the Linux kernel's dm-pcache component. This vulnerability, a use-after-free, occurs within the `kset_replay` function when a stale key's segment generation is accessed after it has been freed. This could allow a local attacker to potentially cause a system crash or lead to other unpredictable system behavior.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-09-11 20:07:03 UTC 
In the Linux kernel, the following vulnerability has been resolved:

dm-pcache: fix use-after-free and invalid seg operations in kset_replay()

In kset_replay, when key->seg_gen is stale (key->seg_gen <
key->cache_pos.cache_seg->gen), cache_key_put(key) is called but then
key->cache_pos.cache_seg is accessed as the argument to cache_seg_get().
This is a use-after-free on the freed key memory. Although mempool
recycled memory is not immediately reclaimed or overwritten in practice,
this is still a potential UAF bug.

Additionally, for expired invalid keys, setting the cache->seg_map bit
and calling cache_seg_get() is unreasonable since the corresponding
segment data is no longer valid.

Fix both issues by moving cache_seg_get() and __set_bit() after the
gen check, so they only execute for valid keys, and using continue to
skip invalid keys.
Comment 1 Mauro Matteo Cascella 2026-09-14 13:47:45 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-80955.mbox