namespace: never expire a locked mount

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-98978
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-23 13:17:19 UTC
Updated2026-10-23 13:17:19 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: namespace: never expire a locked mount Locked mounts are special. They protect the underlying files and directories from being revealed. do_umount() refuses to unmount locked mounts but shrink_submounts() doesn't. A shrinkable mount can become locked once the owner of a user namespace puts it beneath a locked mount with MOVE_MOUNT_BENEATH. The locked property now moves to the mount at the bottom making it possible to unmount the top mount. So umount() of an unlocked ancestor now expires the bottom mount first and the covered directory is revealed: move_mount(c -> x/hidden, MOVE_MOUNT_BENEATH) = 0 the cover after the lock moved: umount2(x/hidden) = 0 the holder of the lock: umount2(x/hidden) = EINVAL the root of the copy, busy: umount2(x) = EBUSY reads x/hidden/secret: "covered-by-root" So leave a locked mount alone as it dies together with its parent. A plain umount() of an unlocked mount with a locked one below it is EBUSY from now on. It's the same for any other locked child. A lazy umount still takes the whole tree. mark_mounts_for_expiry() never sees a locked mount. lock_mnt_tree() leaves a mount on an expiry list alone and nothing else puts a locked one on such a list. Add an assert for this.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 5ff9d8a65ce80efb509ce4e8051394e9ed2cd942 6b8dc3713a76346d212abab46cbfc8d7070f534c git Not specified
CNA Linux Linux affected 5ff9d8a65ce80efb509ce4e8051394e9ed2cd942 d23265a12e4991ce7aedce670c0b6b598cadb644 git Not specified
CNA Linux Linux affected 5ff9d8a65ce80efb509ce4e8051394e9ed2cd942 f78ddcc872248c7aa1d7e904928441a0be4c6d5d git Not specified
CNA Linux Linux affected 3.12 Not specified
CNA Linux Linux unaffected 3.12 semver Not specified
CNA Linux Linux unaffected 6.18.57 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.11 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/6b8dc3713a76346d212abab46cbfc8d7070f534c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f78ddcc872248c7aa1d7e904928441a0be4c6d5d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d23265a12e4991ce7aedce670c0b6b598cadb644 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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