CVE-2026-98986 (GCVE-0-2026-98986)
Vulnerability from cvelistv5
Published
2026-10-23 12:20
Modified
2026-10-23 12:20
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
namespace: remove the fsnotify marks of a mount namespace in process context
mnt_ns_release() drops the last passive reference of a mount namespace
and removes its fanotify marks via fsnotify_mntns_delete(). That takes
the mutex of every group with a mark on the namespace and the spinlock
of the connector. Fine from process context. But mnt_ns_tree_remove()
hands the reference the namespace was allocated with to call_rcu() and
so the marks are removed from the RCU softirq:
BUG: sleeping function called from invalid context at kernel/locking/mutex.c:623
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 0, name: swapper/3
__mutex_lock+0x113/0x24b0
fsnotify_destroy_marks+0x11b/0x3d0
mnt_ns_release_rcu+0x57/0xa0
rcu_core+0x6b6/0x1e40
and lockdep complains about the connector lock being taken from softirq
context. A fanotify group with a FAN_MARK_MNTNS mark on the mount
namespace of another task is all that's needed. Root in a user
namespace can do that for a mount namespace it owns. The task exits and
the namespace is freed with the mark still on it.
Remove the marks in free_mnt_ns() before the namespace is handed to RCU.
That runs in process context once the last active reference is gone. A
mark is added through a file descriptor to the namespace which holds an
active reference so no mark can show up after that.
References
Impacted products
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"fs/namespace.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "888363d74c3b5d32e2accf217add70f8b38e0e2b",
"status": "affected",
"version": "bf630c40164162ba1d3933c2f5e3397d083e0948",
"versionType": "git"
},
{
"lessThan": "9e820a6becdd955a04adbedfd767253a47eedd9e",
"status": "affected",
"version": "bf630c40164162ba1d3933c2f5e3397d083e0948",
"versionType": "git"
},
{
"lessThan": "1a116222acdcc1bc1a8350727ae6f28907d44594",
"status": "affected",
"version": "bf630c40164162ba1d3933c2f5e3397d083e0948",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"fs/namespace.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.15"
},
{
"lessThan": "6.15",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.57",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.2.*",
"status": "unaffected",
"version": "7.2.11",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.57",
"versionStartIncluding": "6.15",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2.11",
"versionStartIncluding": "6.15",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.3",
"versionStartIncluding": "6.15",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnamespace: remove the fsnotify marks of a mount namespace in process context\n\nmnt_ns_release() drops the last passive reference of a mount namespace\nand removes its fanotify marks via fsnotify_mntns_delete(). That takes\nthe mutex of every group with a mark on the namespace and the spinlock\nof the connector. Fine from process context. But mnt_ns_tree_remove()\nhands the reference the namespace was allocated with to call_rcu() and\nso the marks are removed from the RCU softirq:\n\n BUG: sleeping function called from invalid context at kernel/locking/mutex.c:623\n in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 0, name: swapper/3\n __mutex_lock+0x113/0x24b0\n fsnotify_destroy_marks+0x11b/0x3d0\n mnt_ns_release_rcu+0x57/0xa0\n rcu_core+0x6b6/0x1e40\n\nand lockdep complains about the connector lock being taken from softirq\ncontext. A fanotify group with a FAN_MARK_MNTNS mark on the mount\nnamespace of another task is all that\u0027s needed. Root in a user\nnamespace can do that for a mount namespace it owns. The task exits and\nthe namespace is freed with the mark still on it.\n\nRemove the marks in free_mnt_ns() before the namespace is handed to RCU.\nThat runs in process context once the last active reference is gone. A\nmark is added through a file descriptor to the namespace which holds an\nactive reference so no mark can show up after that."
}
],
"providerMetadata": {
"dateUpdated": "2026-10-23T12:20:04.966Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/888363d74c3b5d32e2accf217add70f8b38e0e2b"
},
{
"url": "https://git.kernel.org/stable/c/9e820a6becdd955a04adbedfd767253a47eedd9e"
},
{
"url": "https://git.kernel.org/stable/c/1a116222acdcc1bc1a8350727ae6f28907d44594"
}
],
"title": "namespace: remove the fsnotify marks of a mount namespace in process context",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-98986",
"datePublished": "2026-10-23T12:20:04.966Z",
"dateReserved": "2026-09-25T10:25:14.384Z",
"dateUpdated": "2026-10-23T12:20:04.966Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
Loading…
Loading…
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
Loading…
Loading…