CVE-2026-99175 (GCVE-0-2026-99175)
Vulnerability from cvelistv5
Published
2026-10-28 10:35
Modified
2026-10-28 10:35
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
fsnotify: prevent mark additions during connector teardown
fsnotify_destroy_marks() keeps a reference to its current mark while it
drops conn->lock to destroy the mark. This stabilizes the forward-walk
cursor, but does not prevent a new mark from being inserted before it.
For example, an inotify watch re-added after IN_IGNORED sorts before the
old, detached mark for the same group. The walk can miss the replacement
and then detach the entire connector from the object.
The replacement is still on its group's marks_list and, for inotify, in
the watch IDR. The group mutex no longer protects the connector's object
from disappearing. An unprivileged fdinfo read racing the final detach
can consequently call igrab(NULL):
BUG: KASAN: null-ptr-deref in igrab+0x24/0x100
Write of size 4 at addr 0000000000000148
Call Trace:
igrab+0x24/0x100
inotify_show_fdinfo+0x1dc/0x5e0
seq_show+0x397/0x690
Set a DESTROYING flag under conn->lock before starting the walk, and
reject new marks on that connector with -ENOENT. The existing add-mark
error paths undo the temporary group-list entry and the backend's watch
allocation. Do not wait for teardown while holding the group mutex,
which the destroyer needs. Once the old connector is detached, an add
can install a fresh connector as before.
This closes the insertion race for all object types using the common
connector teardown, without changing the mark reference or SRCU lifetime
rules.
References
Impacted products
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"fs/notify/mark.c",
"include/linux/fsnotify_backend.h"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "952501bfc6e5e654ac4a17ec9d90c1ec614bd9f1",
"status": "affected",
"version": "6b3f05d24d355f50f3d9814304650fcab0efb482",
"versionType": "git"
},
{
"lessThan": "472589eacdf10b5f9bd10b333957ed5291b2544b",
"status": "affected",
"version": "6b3f05d24d355f50f3d9814304650fcab0efb482",
"versionType": "git"
},
{
"lessThan": "36ebddca56b9d8993d6dc984fdecc748ee1f5e06",
"status": "affected",
"version": "6b3f05d24d355f50f3d9814304650fcab0efb482",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"fs/notify/mark.c",
"include/linux/fsnotify_backend.h"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "4.12"
},
{
"lessThan": "4.12",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.59",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.2.*",
"status": "unaffected",
"version": "7.2.13",
"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": "6.18.59",
"versionStartIncluding": "4.12",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2.13",
"versionStartIncluding": "4.12",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.3",
"versionStartIncluding": "4.12",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfsnotify: prevent mark additions during connector teardown\n\nfsnotify_destroy_marks() keeps a reference to its current mark while it\ndrops conn-\u003elock to destroy the mark. This stabilizes the forward-walk\ncursor, but does not prevent a new mark from being inserted before it.\nFor example, an inotify watch re-added after IN_IGNORED sorts before the\nold, detached mark for the same group. The walk can miss the replacement\nand then detach the entire connector from the object.\n\nThe replacement is still on its group\u0027s marks_list and, for inotify, in\nthe watch IDR. The group mutex no longer protects the connector\u0027s object\nfrom disappearing. An unprivileged fdinfo read racing the final detach\ncan consequently call igrab(NULL):\n\n BUG: KASAN: null-ptr-deref in igrab+0x24/0x100\n Write of size 4 at addr 0000000000000148\n Call Trace:\n igrab+0x24/0x100\n inotify_show_fdinfo+0x1dc/0x5e0\n seq_show+0x397/0x690\n\nSet a DESTROYING flag under conn-\u003elock before starting the walk, and\nreject new marks on that connector with -ENOENT. The existing add-mark\nerror paths undo the temporary group-list entry and the backend\u0027s watch\nallocation. Do not wait for teardown while holding the group mutex,\nwhich the destroyer needs. Once the old connector is detached, an add\ncan install a fresh connector as before.\n\nThis closes the insertion race for all object types using the common\nconnector teardown, without changing the mark reference or SRCU lifetime\nrules."
}
],
"providerMetadata": {
"dateUpdated": "2026-10-28T10:35:29.760Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/952501bfc6e5e654ac4a17ec9d90c1ec614bd9f1"
},
{
"url": "https://git.kernel.org/stable/c/472589eacdf10b5f9bd10b333957ed5291b2544b"
},
{
"url": "https://git.kernel.org/stable/c/36ebddca56b9d8993d6dc984fdecc748ee1f5e06"
}
],
"title": "fsnotify: prevent mark additions during connector teardown",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-99175",
"datePublished": "2026-10-28T10:35:29.760Z",
"dateReserved": "2026-09-25T10:25:14.399Z",
"dateUpdated": "2026-10-28T10:35:29.760Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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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.
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