namei: don't reveal overmounted entries in refwalk
In the Linux kernel, the following vulnerability has been resolved: namei: don't reveal overmounted entries in refwalk In rcuwalk the dentry is validated before it is accepted. step_into() step_into() rechecks d_seq and __follow_mount_rcu() rechecks mount_lock. An entry that gets unlinked in between causes the lookup to retry and miss. A refwalk doesn't do this. lookup_fast() takes a reference on the hashed dentry and simply accepts it. So an unlink that happens after the reference was taken isn't seen by refwalk. That's fine for a simple file. We just happened to open it before it was unlinked, no problem. For a mountpoint and specifically a locked mountpoint it very much isn't. The unlink detaches all mounts and then removes the name. Any refwalk that hasn't traversed the mounts yet simply reveals the underlying entry. It's a very narrow window but it can be hit: reads of a covered file in 60 s, 3 walkers, ~15000 unlinks no widening 27 that step + 200 us 3741 See the appended patch for a more reliable reproducer. So check the entry after step_into(). unlink(), rmdir() and rename() mark the dentry with dont_mount() before they detach the mounts and remove the dentry. So a dentry that is marked with DCACHE_CANT_MOUNT and is unhashed by the time its mounts were looked at is a name that was unlinked under the refwalk. DCACHE_CANT_MOUNT is read after the mounts were looked up and it is set before they are detached by detach_mounts(). A refwalk that missed the mounts will see DCA
CVE-2026-98980
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-98980
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "8ed936b5671bfb33d89bc60bdcc7cf0470ba52fe",
"lessThan": "e2b10181d913b4efa3a8dc67a532f859aa5f95e0",
"versionType": "git"
},
{
"status": "affected",
"version": "8ed936b5671bfb33d89bc60bdcc7cf0470ba52fe",
"lessThan": "5f97df8ca7fadf5b53954f50073445ba193902c0",
"versionType": "git"
},
{
"status": "affected",
"version": "8ed936b5671bfb33d89bc60bdcc7cf0470ba52fe",
"lessThan": "b43ff2deef48260bfbdc0dcb520f7929bd3e4007",
"versionType": "git"
},
{
"status": "affected",
"version": "8ed936b5671bfb33d89bc60bdcc7cf0470ba52fe",
"lessThan": "8189ab688f5a2c745dc90b63374da02f213d6994",
"versionType": "git"
}
],
"programFiles": [
"fs/namei.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "3.18"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "3.18",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.12.113",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.57",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.11",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"fs/namei.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-98980
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #55719 · Revision 1
- Added to Heist Feed
- Publisher date