FKIE_CVE-2026-52977

Vulnerability from fkie_nvd - Published: 2026-06-24 17:17 - Updated: 2026-06-24 17:17
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: futex: Prevent lockup in requeue-PI during signal/ timeout wakeup During wait-requeue-pi (task A) and requeue-PI (task B) the following race can happen: Task A Task B futex_wait_requeue_pi() futex_setup_timer() futex_do_wait() futex_requeue() CLASS(hb, hb1)(&key1); CLASS(hb, hb2)(&key2); *timeout* futex_requeue_pi_wakeup_sync() requeue_state = Q_REQUEUE_PI_IGNORE *blocks on hb->lock* futex_proxy_trylock_atomic() futex_requeue_pi_prepare() Q_REQUEUE_PI_IGNORE => -EAGAIN double_unlock_hb(hb1, hb2) *retry* Task B acquires both hb locks and attempts to acquire the PI-lock of the top most waiter (task B). Task A is leaving early due to a signal/ timeout and started removing itself from the queue. It updates its requeue_state but can not remove it from the list because this requires the hb lock which is owned by task B. Usually task A is able to swoop the lock after task B unlocked it. However if task B is of higher priority then task A may not be able to wake up in time and acquire the lock before task B gets it again. Especially on a UP system where A is never scheduled. As a result task A blocks on the lock and task B busy loops, trying to make progress but live locks the system instead. Tragic. This can be fixed by removing the top most waiter from the list in this case. This allows task B to grab the next top waiter (if any) in the next iteration and make progress. Remove the top most waiter if futex_requeue_pi_prepare() fails. Let the waiter conditionally remove itself from the list in handle_early_requeue_pi_wakeup().
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0304d60abb9dcc02bc7fe6d1850f4ca206e8f1a0
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0aacb6d18f76552e3e0ee25d9f40d21b3486f4cf
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/4e0ed44e51727d56244a822ab941efe507c47966
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/69a7cfc66405aeaa2483147653d031b3592ffc9c
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/bc7304f3ae20972d11db6e0b1b541c63feda5f05
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e3f95b1ba242e37093305812df7fdbe7288a43ac
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/futex/requeue.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "4e0ed44e51727d56244a822ab941efe507c47966",
              "status": "affected",
              "version": "07d91ef510fb16a2e0ca7453222105835b7ba3b8",
              "versionType": "git"
            },
            {
              "lessThan": "e3f95b1ba242e37093305812df7fdbe7288a43ac",
              "status": "affected",
              "version": "07d91ef510fb16a2e0ca7453222105835b7ba3b8",
              "versionType": "git"
            },
            {
              "lessThan": "0aacb6d18f76552e3e0ee25d9f40d21b3486f4cf",
              "status": "affected",
              "version": "07d91ef510fb16a2e0ca7453222105835b7ba3b8",
              "versionType": "git"
            },
            {
              "lessThan": "69a7cfc66405aeaa2483147653d031b3592ffc9c",
              "status": "affected",
              "version": "07d91ef510fb16a2e0ca7453222105835b7ba3b8",
              "versionType": "git"
            },
            {
              "lessThan": "0304d60abb9dcc02bc7fe6d1850f4ca206e8f1a0",
              "status": "affected",
              "version": "07d91ef510fb16a2e0ca7453222105835b7ba3b8",
              "versionType": "git"
            },
            {
              "lessThan": "bc7304f3ae20972d11db6e0b1b541c63feda5f05",
              "status": "affected",
              "version": "07d91ef510fb16a2e0ca7453222105835b7ba3b8",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "kernel/futex/requeue.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.15"
            },
            {
              "lessThan": "5.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.175",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.141",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.91",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.33",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.10",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfutex: Prevent lockup in requeue-PI during signal/ timeout wakeup\n\nDuring wait-requeue-pi (task A) and requeue-PI (task B) the following\nrace can happen:\n\n     Task A                             Task B\n  futex_wait_requeue_pi()\n    futex_setup_timer()\n    futex_do_wait()\n                                   futex_requeue()\n                                        CLASS(hb, hb1)(\u0026key1);\n                                        CLASS(hb, hb2)(\u0026key2);\n        *timeout*\n    futex_requeue_pi_wakeup_sync()\n        requeue_state = Q_REQUEUE_PI_IGNORE\n\n    *blocks on hb-\u003elock*\n\n                                        futex_proxy_trylock_atomic()\n                                          futex_requeue_pi_prepare()\n                                            Q_REQUEUE_PI_IGNORE =\u003e -EAGAIN\n                                        double_unlock_hb(hb1, hb2)\n                                         *retry*\n\nTask B acquires both hb locks and attempts to acquire the PI-lock of the\ntop most waiter (task B). Task A is leaving early due to a signal/\ntimeout and started removing itself from the queue. It updates its\nrequeue_state but can not remove it from the list because this requires\nthe hb lock which is owned by task B.\n\nUsually task A is able to swoop the lock after task B unlocked it.\nHowever if task B is of higher priority then task A may not be able to\nwake up in time and acquire the lock before task B gets it again.\nEspecially on a UP system where A is never scheduled.\n\nAs a result task A blocks on the lock and task B busy loops, trying to\nmake progress but live locks the system instead. Tragic.\n\nThis can be fixed by removing the top most waiter from the list in this\ncase. This allows task B to grab the next top waiter (if any) in the\nnext iteration and make progress.\n\nRemove the top most waiter if futex_requeue_pi_prepare() fails.\nLet the waiter conditionally remove itself from the list in\nhandle_early_requeue_pi_wakeup()."
    }
  ],
  "id": "CVE-2026-52977",
  "lastModified": "2026-06-24T17:17:08.293",
  "metrics": {},
  "published": "2026-06-24T17:17:08.293",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/0304d60abb9dcc02bc7fe6d1850f4ca206e8f1a0"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/0aacb6d18f76552e3e0ee25d9f40d21b3486f4cf"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/4e0ed44e51727d56244a822ab941efe507c47966"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/69a7cfc66405aeaa2483147653d031b3592ffc9c"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/bc7304f3ae20972d11db6e0b1b541c63feda5f05"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/e3f95b1ba242e37093305812df7fdbe7288a43ac"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.