nfsd: release path refs on follow_down() error

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-89707
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-11 20:19:58 UTC
Updated2026-09-11 20:19:58 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: nfsd: release path refs on follow_down() error nfsd_cross_mnt() initializes a local struct path with mntget() and dget() before calling follow_down(). On a negative return the error arm jumps to out without releasing those references: err = follow_down(&path, follow_flags); if (err < 0) goto out; follow_down() never drops the caller's entry-time refs on any error sub-case; for example a pre-cross d_manage() failure leaves path untouched, so the mntget()/dget() taken on entry survive the call. Every other early-exit arm in nfsd_cross_mnt() (other-namespace return, IS_ERR(exp2), and the success tail after the swap) already calls path_put(&path); the err < 0 arm is the lone omission. The leak inflates mnt_count and d_count on each failed cross-mount, blocking umount and pinning dentries against the shrinker, and is reachable by any authenticated NFS client through nfsd_lookup_dentry or the NFSv4 READDIR encode path. Fix by calling path_put(&path) before the goto out in the err < 0 arm so the entry-time refs are released on all follow_down() error returns.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected cc53ce53c86924bfe98a12ea20b7465038a08792 194316df81263519156ebe714c4a286bee00e5be git Not specified
CNA Linux Linux affected cc53ce53c86924bfe98a12ea20b7465038a08792 467d56fd3ff57447a790c6dc3ede2d02a947d224 git Not specified
CNA Linux Linux affected cc53ce53c86924bfe98a12ea20b7465038a08792 2bc4343308d85ee4e0dd3877b384306c96f114c2 git Not specified
CNA Linux Linux affected cc53ce53c86924bfe98a12ea20b7465038a08792 6cba08dc1922140d260cfeb30bbda4ee1bf869d8 git Not specified
CNA Linux Linux affected 2.6.38 Not specified
CNA Linux Linux unaffected 2.6.38 semver Not specified
CNA Linux Linux unaffected 6.12.109 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.50 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/194316df81263519156ebe714c4a286bee00e5be 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/467d56fd3ff57447a790c6dc3ede2d02a947d224 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/6cba08dc1922140d260cfeb30bbda4ee1bf869d8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2bc4343308d85ee4e0dd3877b384306c96f114c2 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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