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net/smc: fix TOCTOU race between smc_listen_out() and listener close

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: net/smc: fix TOCTOU race between smc_listen_out() and listener close smc_listen_out() reads lsmc->sk.sk_state without the listener lock, then acquires lock_sock_nested() only after the check passes. This opens a window where smc_close_active() can transition the listener to SMC_CLOSED, call smc_close_cleanup_listen() to drain the accept queue, and release the lock, all between the lockless read and the delayed lock acquisition: smc_listen_work (smc_hs_wq) smc_close_active() ------------------------------- ------------------------- release_sock(child) if (sk_state == SMC_LISTEN) TRUE lock_sock(listener) sk_state = SMC_CLOSED smc_close_cleanup_listen() release_sock(listener) flush_work(tcp_listen_work) lock_sock_nested(listener) smc_accept_enqueue(listener, child) /* child enqueued on dead listener */ smc_close_active() flushes only tcp_listen_work. Work items already dispatched onto smc_hs_wq for the CLC handshake continue running unguarded. smc_accept_enqueue() takes a sock_hold() on the child that is never released, so the child smc_sock, its clcsock, and the reference all leak. A remote peer that opens TCP connections while the server calls close() can exhaust kernel memory. Move lock_sock_nested() to before the sk_state check so that the test and the enqueue are atomic under the listener lock.

Announced Source revision 1
Original source ↗

CVE-2026-74692

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-2026-74692

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
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Prerequisites
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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": "fd57770dd198f5b2ddd5b9e6bf282cf98d63adb9",
        "lessThan": "53c7938d8bcfde3296ec1a347ba2a9393c1fdcfa",
        "versionType": "git"
      },
      {
        "status": "affected",
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        "lessThan": "feb71634bb1abab3e8fb5cde874b27001cc1282e",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "fd57770dd198f5b2ddd5b9e6bf282cf98d63adb9",
        "lessThan": "01865e1ddb126b25ac9eba5cdd7ec49e11183a64",
        "versionType": "git"
      },
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        "versionType": "git"
      },
      {
        "status": "affected",
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        "lessThan": "ff5bcd804b5bc5c64736b7d318c20e12ea9506b8",
        "versionType": "git"
      },
      {
        "status": "affected",
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        "lessThan": "185a4caeecabc150106deda1da170b09f2ad803f",
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      },
      {
        "status": "affected",
        "version": "d1d004585b40c212b338fc8a40cbaaf230ea4703",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4.19.299",
        "lessThan": "4.20",
        "versionType": "semver"
      }
    ],
    "programFiles": [
      "net/smc/af_smc.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "5.1"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "5.1",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.15.216",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.183",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.152",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.104",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.45",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.1.9",
        "versionType": "semver",
        "lessThanOrEqual": "7.1.*"
      },
      {
        "status": "unaffected",
        "version": "7.2",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/smc/af_smc.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-74692

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#34272 · Revision 1
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