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net/smc: fix NULL dereference and UAF in smc_tcp_syn_recv_sock()

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: net/smc: fix NULL dereference and UAF in smc_tcp_syn_recv_sock() Syzkaller reported a panic in smc_tcp_syn_recv_sock() [1]. smc_tcp_syn_recv_sock() is called in the TCP receive path (softirq) via icsk_af_ops->syn_recv_sock on the clcsock (TCP listening socket). It reads sk_user_data to get the smc_sock pointer. However, when the SMC listen socket is being closed concurrently, smc_close_active() sets clcsock->sk_user_data to NULL under sk_callback_lock, and then the smc_sock itself can be freed via sock_put() in smc_release(). This leads to two issues: 1) NULL pointer dereference: sk_user_data is NULL when accessed. 2) Use-after-free: sk_user_data is read as non-NULL, but the smc_sock is freed before its fields (e.g., queued_smc_hs, ori_af_ops) are accessed. The race window looks like this (the syzkaller crash [1] triggers via the SYN cookie path: tcp_get_cookie_sock() -> smc_tcp_syn_recv_sock(), but the normal tcp_check_req() path has the same race): CPU A (softirq) CPU B (process ctx) tcp_v4_rcv() TCP_NEW_SYN_RECV: sk = req->rsk_listener sock_hold(sk) /* No lock on listener */ smc_close_active(): write_lock_bh(cb_lock) sk_user_data = NULL write_unlock_bh(cb_lock) ... smc_clcsock_release() sock_put(smc->sk) x2 -> smc_sock freed! tcp_check_req() smc_tcp_syn_recv_sock(): smc = user_data(sk) -> NULL or dangling smc->queued_smc_hs -> crash! Note that the clcsock and smc_sock are two independent objects with separ

Announced Source revision 1
Original source ↗

CVE-2026-23450

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-2026-23450

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": "ebfee3e153f67c8b38eb94a7062ee94aa6f92708",
        "lessThan": "f315277856caeafcd996c2611afc085ca2d53275",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "8270d9c21041470f58348248b9d9dcf3bf79592e",
        "lessThan": "1e4f873879e075bbd4eb1c644d6933303ac5eba4",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "8270d9c21041470f58348248b9d9dcf3bf79592e",
        "lessThan": "f00fc26c8a06442b225a350fe000c0a11483e6a3",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "8270d9c21041470f58348248b9d9dcf3bf79592e",
        "lessThan": "cadf3da46c15523fba90d80c9955f536ee3b4023",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "8270d9c21041470f58348248b9d9dcf3bf79592e",
        "lessThan": "fd7579f0a2c84ba8a7d4f206201b50dc8ddf90c2",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "8270d9c21041470f58348248b9d9dcf3bf79592e",
        "lessThan": "1fab5ece76fb42a761178dcd0ebcbf578377b0dd",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "8270d9c21041470f58348248b9d9dcf3bf79592e",
        "lessThan": "6d5e4538364b9ceb1ac2941a4deb86650afb3538",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "5.15.174",
        "lessThan": "5.15.203",
        "versionType": "semver"
      }
    ],
    "programFiles": [
      "net/smc/af_smc.c",
      "net/smc/smc.h",
      "net/smc/smc_close.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "5.18"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "5.18",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.15.203",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.167",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.130",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.78",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.20",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "6.19.10",
        "versionType": "semver",
        "lessThanOrEqual": "6.19.*"
      },
      {
        "status": "unaffected",
        "version": "7.0",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/smc/af_smc.c",
      "net/smc/smc.h",
      "net/smc/smc_close.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-23450

Source reference: /cveMetadata/cveId

Publisher severity

critical

Source reference: /containers/cna/metrics

Event
#39855 · Revision 1
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Publisher date
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