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inotify: fix watch count leak when fsnotify_add_inode_mark_locked() fails

Type: advisorySources: OSV

In the Linux kernel, the following vulnerability has been resolved: inotify: fix watch count leak when fsnotify_add_inode_mark_locked() fails When fsnotify_add_inode_mark_locked() fails in inotify_new_watch(), the error path calls inotify_remove_from_idr() but does not call dec_inotify_watches() to undo the preceding inc_inotify_watches(). This leaks a watch count, and repeated failures can exhaust the max_user_watches limit with -ENOSPC even when no watches are active. Prior to commit 1cce1eea0aff ("inotify: Convert to using per-namespace limits"), the watch count was incremented after fsnotify_add_mark_locked() succeeded, so this path was not affected. The conversion moved inc_inotify_watches() before the mark insertion without adding the corresponding rollback. Add the missing dec_inotify_watches() call in the error path.

Products
Kernel
Affected versions
Not specified
Fixed versions
5.10.258, 5.15.209, 6.1.175, 6.12.86, 6.18.27, 6.6.140, 7.0.4
CVEs
CVE-2026-46040
Confirmed fixed CVEs
Not specified
Updated in this feed
8 Nov 2026, 00:39 UTC · Revision 1

Source evidence

inotify: fix watch count leak when fsnotify_add_inode_mark_locked() fails

core-osv · Original source

Published 27 May 2026, 12:56 UTC

In the Linux kernel, the following vulnerability has been resolved: inotify: fix watch count leak when fsnotify_add_inode_mark_locked() fails When fsnotify_add_inode_mark_locked() fails in inotify_new_watch(), the error path calls inotify_remove_from_idr() but does not call dec_inotify_watches() to undo the preceding inc_inotify_watches(). This leaks a watch count, and repeated failures can exhaust the max_user_watches limit with -ENOSPC even when no watches are active. Prior to commit 1cce1eea0aff ("inotify: Convert to using per-namespace limits"), the watch count was incremented after fsnotify_add_mark_locked() succeeded, so this path was not affected. The conversion moved inc_inotify_watches() before the mark insertion without adding the corresponding rollback. Add the missing dec_inotify_watches() call in the error path.

osv:CVE-2026-46040

Kernel

Fixed versions: 5.10.258, 5.15.209, 6.1.175, 6.6.140, 6.12.86, 6.18.27, 7.0.4

Complete source record
{
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  "url": "https://osv.dev/vulnerability/CVE-2026-46040",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "inotify: fix watch count leak when fsnotify_add_inode_mark_locked() fails",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: inotify: fix watch count leak when fsnotify_add_inode_mark_locked() fails When fsnotify_add_inode_mark_locked() fails in inotify_new_watch(), the error path calls inotify_remove_from_idr() but does not call dec_inotify_watches() to undo the preceding inc_inotify_watches(). This leaks a watch count, and repeated failures can exhaust the max_user_watches limit with -ENOSPC even when no watches are active. Prior to commit 1cce1eea0aff (\"inotify: Convert to using per-namespace limits\"), the watch count was incremented after fsnotify_add_mark_locked() succeeded, so this path was not affected. The conversion moved inc_inotify_watches() before the mark insertion without adding the corresponding rollback. Add the missing dec_inotify_watches() call in the error path.",
    "evidence": "osv:CVE-2026-46040",
    "products": [
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        "prerequisites": [],
        "fixed_versions": [
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            "evidence": "/affected/1/ranges"
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            "value": "7.0.4",
            "evidence": "/affected/1/ranges"
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      }
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    "severity": "unknown",
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            {
              "type": "ECOSYSTEM",
              "events": [
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                  "introduced": "5.16.0"
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              ]
            },
            {
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                  "introduced": "6.2.0"
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            "ecosystem": "Linux"
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      ],
      "modified": "2026-10-28T02:30:52.343651953Z",
      "provider": "osv",
      "references": [
        "https://cert-portal.siemens.com/productcert/html/ssa-019113.html",
        "https://cert-portal.siemens.com/productcert/html/ssa-457936.html",
        "https://cert-portal.siemens.com/productcert/html/ssa-784472.html",
        "https://git.kernel.org/stable/c/10edf7e0ffdc7faa18e2244b17722c1b882b8273",
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        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/46xxx/CVE-2026-46040.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-46040",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/46xxx/CVE-2026-46040.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-46040",
        "evidence": "/id"
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    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 521037,
  "published_at": "2026-05-27T12:56:52.161+00:00"
}