CVE-2026-93191 (GCVE-0-2026-93191)
Vulnerability from cvelistv5
Published
2026-09-17 16:12
Modified
2026-10-19 09:07
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: smack: fix incorrect task context in smack_msg_queue_msgrcv The smack_msg_queue_msgrcv() function incorrectly checks the permissions of the 'current' task instead of the 'target' task. In the msgsnd() syscall path, if a receiver is already waiting, the pipelined_send() optimization is used to push the message directly to the receiver task: ipc/msg.c`pipelined_send(): ` smp_store_release(&msr->r_msg, msg) In this case, the 'sender' (current) task performs the check on behalf of the 'receiver' task (msr->r_tsk, passed as the 'target' parameter): ipc/msg.c`pipelined_send(): ` security_msg_queue_msgrcv(,, target := msr->r_tsk,,) However, smack_msg_queue_msgrcv() ignores the 'target' and checks 'current': smack_msg_queue_msgrcv(…) ` smk_curacc_msq(isp, MAY_READWRITE); // current task 'current' MAY satisfy smack_msg_queue_msgrcv r/w requirement, but 'target' (the receiver task) might NOT; as a result, an unauthorized receiver gets the message, violating MAC policy. Test: 1) create a sysv message queue with label “foo” 2) echo "bar foo r" >/smack/load2 3) msgrcv(,,,0,MSG_NOERROR) in "bar"-labeled task. The task is waiting for the messages ... 4) msgsnd() from a "foo"-labeled task: "bar"-labeled task gets the message. This patch fixes the issue by checking permission on the 'target' task instead of 'current'. (2008-02-04, Casey Schaufler)
References
Impacted products
Vendor Product Version
Linux Linux Version: e114e473771c848c3cfec05f0123e70f1cdbdc99
Version: e114e473771c848c3cfec05f0123e70f1cdbdc99
Version: e114e473771c848c3cfec05f0123e70f1cdbdc99
Version: e114e473771c848c3cfec05f0123e70f1cdbdc99
Version: e114e473771c848c3cfec05f0123e70f1cdbdc99
Version: e114e473771c848c3cfec05f0123e70f1cdbdc99
Version: e114e473771c848c3cfec05f0123e70f1cdbdc99
Version: e114e473771c848c3cfec05f0123e70f1cdbdc99
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmack: fix incorrect task context in smack_msg_queue_msgrcv\n\nThe smack_msg_queue_msgrcv() function incorrectly checks\nthe permissions of the \u0027current\u0027 task instead of the\n\u0027target\u0027 task.\n\nIn the msgsnd() syscall path, if a receiver is already waiting,\nthe pipelined_send() optimization is used to push the message\ndirectly to the receiver task:\n\n    ipc/msg.c`pipelined_send():\n    ` smp_store_release(\u0026msr-\u003er_msg, msg)\n\nIn this case, the \u0027sender\u0027 (current) task performs the check\non behalf of the \u0027receiver\u0027 task (msr-\u003er_tsk, passed as the\n\u0027target\u0027 parameter):\n\n  ipc/msg.c`pipelined_send():\n  ` security_msg_queue_msgrcv(,, target := msr-\u003er_tsk,,)\n\nHowever, smack_msg_queue_msgrcv() ignores the \u0027target\u0027 and\nchecks \u0027current\u0027:\n\n  smack_msg_queue_msgrcv(\u2026)\n  ` smk_curacc_msq(isp, MAY_READWRITE); // current task\n\n\u0027current\u0027 MAY satisfy smack_msg_queue_msgrcv r/w requirement,\nbut \u0027target\u0027 (the receiver task) might NOT;\nas a result, an unauthorized receiver gets the message,\nviolating MAC policy.\n\nTest:\n1) create a sysv message queue with label \u201cfoo\u201d\n2) echo \"bar foo r\" \u003e/smack/load2\n3) msgrcv(,,,0,MSG_NOERROR) in \"bar\"-labeled task.\n    The task is waiting for the messages ...\n4) msgsnd() from a \"foo\"-labeled task:\n\"bar\"-labeled task gets the message.\n\nThis patch fixes the issue by checking permission on the\n\u0027target\u0027 task instead of \u0027current\u0027.\n\n(2008-02-04, Casey Schaufler)"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:07:03.807Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/4e49f997ef0c569e09b42aab6bd38c7c54ea095d"
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        {
          "url": "https://git.kernel.org/stable/c/dbece6c2f80b0470d8d99d7a016827dce99ed6e3"
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          "url": "https://git.kernel.org/stable/c/7be4bd21c50afa83c93799b0f16cf5bfa493194e"
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        {
          "url": "https://git.kernel.org/stable/c/ec47f4177046dfaaf1cebb15f4d2e7b543475daf"
        },
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          "url": "https://git.kernel.org/stable/c/e35dc5a4ed6d1e536382d80c685187511ff248a1"
        },
        {
          "url": "https://git.kernel.org/stable/c/c2ab27c2e11591524b1378c24ad18882a425d1fa"
        },
        {
          "url": "https://git.kernel.org/stable/c/d02c55e3ea82e41ea2c2026e08201e5daa4d0cfe"
        },
        {
          "url": "https://git.kernel.org/stable/c/fba3d32825f4bbc8e20f0cdc3b14df57965b8fe5"
        }
      ],
      "title": "smack: fix incorrect task context in smack_msg_queue_msgrcv",
      "x_generator": {
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-93191",
    "datePublished": "2026-09-17T16:12:15.765Z",
    "dateReserved": "2026-09-17T16:02:15.092Z",
    "dateUpdated": "2026-10-19T09:07:03.807Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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