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nfsd: fix fcache_disposal UAF by inlining dispose state into nfsd_net

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: nfsd: fix fcache_disposal UAF by inlining dispose state into nfsd_net nfsd_file_dispose_list_delayed() defers fput() to nfsd service threads via a per-net freeme queue, preventing the shrinker and GC worker from bearing the cost of closing files (see ffb402596147). However, the queue lives in a separately-allocated struct nfsd_fcache_disposal that is freed by nfsd_free_fcache_disposal_net() during per-net teardown. The global shrinker, laundrette, and fsnotify callbacks can still be inside nfsd_file_dispose_list_delayed() dereferencing that pointer, causing a use-after-free. Inline the spinlock and freeme list directly into struct nfsd_net (as fcache_dispose_lock and fcache_dispose_list), eliminating the separately allocated struct nfsd_fcache_disposal entirely. These fields now have the same lifetime as the net namespace itself, so there is no dangling pointer to chase. nfsd_file_cache_start_net() now just initializes the inline fields and cannot fail due to allocation. nfsd_file_cache_shutdown_net() drains the inline list directly instead of freeing a separate struct. The alloc/free helpers are removed.

Announced Source revision 1
Original source ↗

CVE-2026-89682

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-2026-89682

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": "1463b38e7cf34d4cc60f41daff459ad807b2e408",
        "lessThan": "e6c3a43d0a41f03abae3764fc82a59369360c7e0",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1463b38e7cf34d4cc60f41daff459ad807b2e408",
        "lessThan": "9c8ac7c2b9b150e13b7ad0d0fae54f17747dce67",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1463b38e7cf34d4cc60f41daff459ad807b2e408",
        "lessThan": "ba0ee9e04b7a0356c28d5a2fe445db675d24e572",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1463b38e7cf34d4cc60f41daff459ad807b2e408",
        "lessThan": "cadc9036d5a8209f89e7026ddba7cfb1c716b03c",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1463b38e7cf34d4cc60f41daff459ad807b2e408",
        "lessThan": "bbf13732f74351d21c5e0e8dd9bd8e1c48dc35d4",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "e8f923e1e9fcc0832a12c8a2461792e5a9544c03",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "3bc94fb44f10ef852723e1aeaac6794c5ab16aec",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "5.10.220",
        "lessThan": "5.11",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "5.15.154",
        "lessThan": "5.16",
        "versionType": "semver"
      }
    ],
    "programFiles": [
      "fs/nfsd/filecache.c",
      "fs/nfsd/netns.h"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "5.17"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "5.17",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.6.160",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.114",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.51",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.2.4",
        "versionType": "semver",
        "lessThanOrEqual": "7.2.*"
      },
      {
        "status": "unaffected",
        "version": "7.3",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "fs/nfsd/filecache.c",
      "fs/nfsd/netns.h"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-89682

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#46706 · Revision 1
Added to Heist Feed
Publisher date
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