CVE-2025-71126 (GCVE-0-2025-71126)
Vulnerability from cvelistv5
Published
2026-01-14 15:06
Modified
2026-02-09 08:35
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: mptcp: avoid deadlock on fallback while reinjecting Jakub reported an MPTCP deadlock at fallback time: WARNING: possible recursive locking detected 6.18.0-rc7-virtme #1 Not tainted -------------------------------------------- mptcp_connect/20858 is trying to acquire lock: ff1100001da18b60 (&msk->fallback_lock){+.-.}-{3:3}, at: __mptcp_try_fallback+0xd8/0x280 but task is already holding lock: ff1100001da18b60 (&msk->fallback_lock){+.-.}-{3:3}, at: __mptcp_retrans+0x352/0xaa0 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&msk->fallback_lock); lock(&msk->fallback_lock); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by mptcp_connect/20858: #0: ff1100001da18290 (sk_lock-AF_INET){+.+.}-{0:0}, at: mptcp_sendmsg+0x114/0x1bc0 #1: ff1100001db40fd0 (k-sk_lock-AF_INET#2){+.+.}-{0:0}, at: __mptcp_retrans+0x2cb/0xaa0 #2: ff1100001da18b60 (&msk->fallback_lock){+.-.}-{3:3}, at: __mptcp_retrans+0x352/0xaa0 stack backtrace: CPU: 0 UID: 0 PID: 20858 Comm: mptcp_connect Not tainted 6.18.0-rc7-virtme #1 PREEMPT(full) Hardware name: Bochs, BIOS Bochs 01/01/2011 Call Trace: <TASK> dump_stack_lvl+0x6f/0xa0 print_deadlock_bug.cold+0xc0/0xcd validate_chain+0x2ff/0x5f0 __lock_acquire+0x34c/0x740 lock_acquire.part.0+0xbc/0x260 _raw_spin_lock_bh+0x38/0x50 __mptcp_try_fallback+0xd8/0x280 mptcp_sendmsg_frag+0x16c2/0x3050 __mptcp_retrans+0x421/0xaa0 mptcp_release_cb+0x5aa/0xa70 release_sock+0xab/0x1d0 mptcp_sendmsg+0xd5b/0x1bc0 sock_write_iter+0x281/0x4d0 new_sync_write+0x3c5/0x6f0 vfs_write+0x65e/0xbb0 ksys_write+0x17e/0x200 do_syscall_64+0xbb/0xfd0 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x7fa5627cbc5e Code: 4d 89 d8 e8 14 bd 00 00 4c 8b 5d f8 41 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 11 c9 c3 0f 1f 80 00 00 00 00 48 8b 45 10 0f 05 <c9> c3 83 e2 39 83 fa 08 75 e7 e8 13 ff ff ff 0f 1f 00 f3 0f 1e fa RSP: 002b:00007fff1fe14700 EFLAGS: 00000202 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007fa5627cbc5e RDX: 0000000000001f9c RSI: 00007fff1fe16984 RDI: 0000000000000005 RBP: 00007fff1fe14710 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 00007fff1fe16920 R13: 0000000000002000 R14: 0000000000001f9c R15: 0000000000001f9c The packet scheduler could attempt a reinjection after receiving an MP_FAIL and before the infinite map has been transmitted, causing a deadlock since MPTCP needs to do the reinjection atomically from WRT fallback. Address the issue explicitly avoiding the reinjection in the critical scenario. Note that this is the only fallback critical section that could potentially send packets and hit the double-lock.
References
Impacted products
Vendor Product Version
Linux Linux Version: 5586518bec27666c747cd52aabb62d485686d0bf
Version: 75a4c9ab8a7af0d76b31ccd1188ed178c38b35d2
Version: 54999dea879fecb761225e28f274b40662918c30
Version: f8a1d9b18c5efc76784f5a326e905f641f839894
Version: f8a1d9b18c5efc76784f5a326e905f641f839894
Version: 1d82a8fe6ee4afdc92f4e8808c9dad2a6095bbc5
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/mptcp/protocol.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "0107442e82c0f8d6010e07e6030741c59c520d6e",
              "status": "affected",
              "version": "5586518bec27666c747cd52aabb62d485686d0bf",
              "versionType": "git"
            },
            {
              "lessThan": "252892d5a6a2f163ce18f32716e46fa4da7d4e79",
              "status": "affected",
              "version": "75a4c9ab8a7af0d76b31ccd1188ed178c38b35d2",
              "versionType": "git"
            },
            {
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              "status": "affected",
              "version": "54999dea879fecb761225e28f274b40662918c30",
              "versionType": "git"
            },
            {
              "lessThan": "50f47c02be419bf0a3ae94c118addf67beef359f",
              "status": "affected",
              "version": "f8a1d9b18c5efc76784f5a326e905f641f839894",
              "versionType": "git"
            },
            {
              "lessThan": "ffb8c27b0539dd90262d1021488e7817fae57c42",
              "status": "affected",
              "version": "f8a1d9b18c5efc76784f5a326e905f641f839894",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "1d82a8fe6ee4afdc92f4e8808c9dad2a6095bbc5",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/mptcp/protocol.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.16"
            },
            {
              "lessThan": "6.16",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.160",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.120",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.64",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.19",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.160",
                  "versionStartIncluding": "6.1.149",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.120",
                  "versionStartIncluding": "6.6.101",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.64",
                  "versionStartIncluding": "6.12.40",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.3",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "6.15.8",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: avoid deadlock on fallback while reinjecting\n\nJakub reported an MPTCP deadlock at fallback time:\n\n WARNING: possible recursive locking detected\n 6.18.0-rc7-virtme #1 Not tainted\n --------------------------------------------\n mptcp_connect/20858 is trying to acquire lock:\n ff1100001da18b60 (\u0026msk-\u003efallback_lock){+.-.}-{3:3}, at: __mptcp_try_fallback+0xd8/0x280\n\n but task is already holding lock:\n ff1100001da18b60 (\u0026msk-\u003efallback_lock){+.-.}-{3:3}, at: __mptcp_retrans+0x352/0xaa0\n\n other info that might help us debug this:\n  Possible unsafe locking scenario:\n\n        CPU0\n        ----\n   lock(\u0026msk-\u003efallback_lock);\n   lock(\u0026msk-\u003efallback_lock);\n\n  *** DEADLOCK ***\n\n  May be due to missing lock nesting notation\n\n 3 locks held by mptcp_connect/20858:\n  #0: ff1100001da18290 (sk_lock-AF_INET){+.+.}-{0:0}, at: mptcp_sendmsg+0x114/0x1bc0\n  #1: ff1100001db40fd0 (k-sk_lock-AF_INET#2){+.+.}-{0:0}, at: __mptcp_retrans+0x2cb/0xaa0\n  #2: ff1100001da18b60 (\u0026msk-\u003efallback_lock){+.-.}-{3:3}, at: __mptcp_retrans+0x352/0xaa0\n\n stack backtrace:\n CPU: 0 UID: 0 PID: 20858 Comm: mptcp_connect Not tainted 6.18.0-rc7-virtme #1 PREEMPT(full)\n Hardware name: Bochs, BIOS Bochs 01/01/2011\n Call Trace:\n  \u003cTASK\u003e\n  dump_stack_lvl+0x6f/0xa0\n  print_deadlock_bug.cold+0xc0/0xcd\n  validate_chain+0x2ff/0x5f0\n  __lock_acquire+0x34c/0x740\n  lock_acquire.part.0+0xbc/0x260\n  _raw_spin_lock_bh+0x38/0x50\n  __mptcp_try_fallback+0xd8/0x280\n  mptcp_sendmsg_frag+0x16c2/0x3050\n  __mptcp_retrans+0x421/0xaa0\n  mptcp_release_cb+0x5aa/0xa70\n  release_sock+0xab/0x1d0\n  mptcp_sendmsg+0xd5b/0x1bc0\n  sock_write_iter+0x281/0x4d0\n  new_sync_write+0x3c5/0x6f0\n  vfs_write+0x65e/0xbb0\n  ksys_write+0x17e/0x200\n  do_syscall_64+0xbb/0xfd0\n  entry_SYSCALL_64_after_hwframe+0x4b/0x53\n RIP: 0033:0x7fa5627cbc5e\n Code: 4d 89 d8 e8 14 bd 00 00 4c 8b 5d f8 41 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 11 c9 c3 0f 1f 80 00 00 00 00 48 8b 45 10 0f 05 \u003cc9\u003e c3 83 e2 39 83 fa 08 75 e7 e8 13 ff ff ff 0f 1f 00 f3 0f 1e fa\n RSP: 002b:00007fff1fe14700 EFLAGS: 00000202 ORIG_RAX: 0000000000000001\n RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007fa5627cbc5e\n RDX: 0000000000001f9c RSI: 00007fff1fe16984 RDI: 0000000000000005\n RBP: 00007fff1fe14710 R08: 0000000000000000 R09: 0000000000000000\n R10: 0000000000000000 R11: 0000000000000202 R12: 00007fff1fe16920\n R13: 0000000000002000 R14: 0000000000001f9c R15: 0000000000001f9c\n\nThe packet scheduler could attempt a reinjection after receiving an\nMP_FAIL and before the infinite map has been transmitted, causing a\ndeadlock since MPTCP needs to do the reinjection atomically from WRT\nfallback.\n\nAddress the issue explicitly avoiding the reinjection in the critical\nscenario. Note that this is the only fallback critical section that\ncould potentially send packets and hit the double-lock."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-02-09T08:35:21.899Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/0107442e82c0f8d6010e07e6030741c59c520d6e"
        },
        {
          "url": "https://git.kernel.org/stable/c/252892d5a6a2f163ce18f32716e46fa4da7d4e79"
        },
        {
          "url": "https://git.kernel.org/stable/c/0ca9fb4335e726dab4f23b3bfe87271d8f005f41"
        },
        {
          "url": "https://git.kernel.org/stable/c/50f47c02be419bf0a3ae94c118addf67beef359f"
        },
        {
          "url": "https://git.kernel.org/stable/c/ffb8c27b0539dd90262d1021488e7817fae57c42"
        }
      ],
      "title": "mptcp: avoid deadlock on fallback while reinjecting",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-71126",
    "datePublished": "2026-01-14T15:06:11.417Z",
    "dateReserved": "2026-01-13T15:30:19.655Z",
    "dateUpdated": "2026-02-09T08:35:21.899Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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