nfsd: fix fcache_disposal UAF by inlining dispose state into nfsd_net

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-89682
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-11 20:19:55 UTC
Updated2026-09-11 20:19:55 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: nfsd: fix fcache_disposal UAF by inlining dispose state into nfsd_net nfsd_file_dispose_list_delayed() defers fput() to nfsd service threads via a per-net freeme queue, preventing the shrinker and GC worker from bearing the cost of closing files (see ffb402596147). However, the queue lives in a separately-allocated struct nfsd_fcache_disposal that is freed by nfsd_free_fcache_disposal_net() during per-net teardown. The global shrinker, laundrette, and fsnotify callbacks can still be inside nfsd_file_dispose_list_delayed() dereferencing that pointer, causing a use-after-free. Inline the spinlock and freeme list directly into struct nfsd_net (as fcache_dispose_lock and fcache_dispose_list), eliminating the separately allocated struct nfsd_fcache_disposal entirely. These fields now have the same lifetime as the net namespace itself, so there is no dangling pointer to chase. nfsd_file_cache_start_net() now just initializes the inline fields and cannot fail due to allocation. nfsd_file_cache_shutdown_net() drains the inline list directly instead of freeing a separate struct. The alloc/free helpers are removed.

Risk And Classification

EPSS: 0.001660000 probability, percentile 0.061350000 (date 2026-09-12)

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 1463b38e7cf34d4cc60f41daff459ad807b2e408 ba0ee9e04b7a0356c28d5a2fe445db675d24e572 git Not specified
CNA Linux Linux affected 1463b38e7cf34d4cc60f41daff459ad807b2e408 cadc9036d5a8209f89e7026ddba7cfb1c716b03c git Not specified
CNA Linux Linux affected 1463b38e7cf34d4cc60f41daff459ad807b2e408 bbf13732f74351d21c5e0e8dd9bd8e1c48dc35d4 git Not specified
CNA Linux Linux affected e8f923e1e9fcc0832a12c8a2461792e5a9544c03 git Not specified
CNA Linux Linux affected 3bc94fb44f10ef852723e1aeaac6794c5ab16aec git Not specified
CNA Linux Linux affected 5.10.220 5.11 semver Not specified
CNA Linux Linux affected 5.15.154 5.16 semver Not specified
CNA Linux Linux affected 5.17 Not specified
CNA Linux Linux unaffected 5.17 semver Not specified
CNA Linux Linux unaffected 6.18.51 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.4 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/ba0ee9e04b7a0356c28d5a2fe445db675d24e572 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/cadc9036d5a8209f89e7026ddba7cfb1c716b03c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/bbf13732f74351d21c5e0e8dd9bd8e1c48dc35d4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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