CVE-2025-39977 (GCVE-0-2025-39977)
Vulnerability from cvelistv5
Published
2025-10-15 07:55
Modified
2025-10-15 07:55
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: futex: Prevent use-after-free during requeue-PI syzbot managed to trigger the following race: T1 T2 futex_wait_requeue_pi() futex_do_wait() schedule() futex_requeue() futex_proxy_trylock_atomic() futex_requeue_pi_prepare() requeue_pi_wake_futex() futex_requeue_pi_complete() /* preempt */ * timeout/ signal wakes T1 * futex_requeue_pi_wakeup_sync() // Q_REQUEUE_PI_LOCKED futex_hash_put() // back to userland, on stack futex_q is garbage /* back */ wake_up_state(q->task, TASK_NORMAL); In this scenario futex_wait_requeue_pi() is able to leave without using futex_q::lock_ptr for synchronization. This can be prevented by reading futex_q::task before updating the futex_q::requeue_state. A reference on the task_struct is not needed because requeue_pi_wake_futex() is invoked with a spinlock_t held which implies a RCU read section. Even if T1 terminates immediately after, the task_struct will remain valid during T2's wake_up_state(). A READ_ONCE on futex_q::task before futex_requeue_pi_complete() is enough because it ensures that the variable is read before the state is updated. Read futex_q::task before updating the requeue state, use it for the following wakeup.
References
Impacted products
Vendor Product Version
Linux Linux Version: 07d91ef510fb16a2e0ca7453222105835b7ba3b8
Version: 07d91ef510fb16a2e0ca7453222105835b7ba3b8
Version: 07d91ef510fb16a2e0ca7453222105835b7ba3b8
Version: 07d91ef510fb16a2e0ca7453222105835b7ba3b8
Version: 07d91ef510fb16a2e0ca7453222105835b7ba3b8
 Create a notification for this product.
Show details on NVD website

To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "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": "cb5d19a61274b51b49601214a87af573b43d60fa",
              "status": "affected",
              "version": "07d91ef510fb16a2e0ca7453222105835b7ba3b8",
              "versionType": "git"
            },
            {
              "lessThan": "348736955ed6ca6e99ca24b93b1d3fbfe352c181",
              "status": "affected",
              "version": "07d91ef510fb16a2e0ca7453222105835b7ba3b8",
              "versionType": "git"
            },
            {
              "lessThan": "a170b9c0dde83312b8b58ccc91509c7c15711641",
              "status": "affected",
              "version": "07d91ef510fb16a2e0ca7453222105835b7ba3b8",
              "versionType": "git"
            },
            {
              "lessThan": "d824b2dbdcfe3c390278dd9652ea526168ef6850",
              "status": "affected",
              "version": "07d91ef510fb16a2e0ca7453222105835b7ba3b8",
              "versionType": "git"
            },
            {
              "lessThan": "b549113738e8c751b613118032a724b772aa83f2",
              "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": "6.1.155",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.109",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.50",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.16.*",
              "status": "unaffected",
              "version": "6.16.10",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.17",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.155",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.109",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.50",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.16.10",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.17",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfutex: Prevent use-after-free during requeue-PI\n\nsyzbot managed to trigger the following race:\n\n   T1                               T2\n\n futex_wait_requeue_pi()\n   futex_do_wait()\n     schedule()\n                               futex_requeue()\n                                 futex_proxy_trylock_atomic()\n                                   futex_requeue_pi_prepare()\n                                   requeue_pi_wake_futex()\n                                     futex_requeue_pi_complete()\n                                      /* preempt */\n\n         * timeout/ signal wakes T1 *\n\n   futex_requeue_pi_wakeup_sync() // Q_REQUEUE_PI_LOCKED\n   futex_hash_put()\n  // back to userland, on stack futex_q is garbage\n\n                                      /* back */\n                                     wake_up_state(q-\u003etask, TASK_NORMAL);\n\nIn this scenario futex_wait_requeue_pi() is able to leave without using\nfutex_q::lock_ptr for synchronization.\n\nThis can be prevented by reading futex_q::task before updating the\nfutex_q::requeue_state. A reference on the task_struct is not needed\nbecause requeue_pi_wake_futex() is invoked with a spinlock_t held which\nimplies a RCU read section.\n\nEven if T1 terminates immediately after, the task_struct will remain valid\nduring T2\u0027s wake_up_state().  A READ_ONCE on futex_q::task before\nfutex_requeue_pi_complete() is enough because it ensures that the variable\nis read before the state is updated.\n\nRead futex_q::task before updating the requeue state, use it for the\nfollowing wakeup."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-10-15T07:55:58.283Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/cb5d19a61274b51b49601214a87af573b43d60fa"
        },
        {
          "url": "https://git.kernel.org/stable/c/348736955ed6ca6e99ca24b93b1d3fbfe352c181"
        },
        {
          "url": "https://git.kernel.org/stable/c/a170b9c0dde83312b8b58ccc91509c7c15711641"
        },
        {
          "url": "https://git.kernel.org/stable/c/d824b2dbdcfe3c390278dd9652ea526168ef6850"
        },
        {
          "url": "https://git.kernel.org/stable/c/b549113738e8c751b613118032a724b772aa83f2"
        }
      ],
      "title": "futex: Prevent use-after-free during requeue-PI",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-39977",
    "datePublished": "2025-10-15T07:55:58.283Z",
    "dateReserved": "2025-04-16T07:20:57.150Z",
    "dateUpdated": "2025-10-15T07:55:58.283Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-39977\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-10-15T08:15:35.517\",\"lastModified\":\"2025-10-16T15:29:11.563\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nfutex: Prevent use-after-free during requeue-PI\\n\\nsyzbot managed to trigger the following race:\\n\\n   T1                               T2\\n\\n futex_wait_requeue_pi()\\n   futex_do_wait()\\n     schedule()\\n                               futex_requeue()\\n                                 futex_proxy_trylock_atomic()\\n                                   futex_requeue_pi_prepare()\\n                                   requeue_pi_wake_futex()\\n                                     futex_requeue_pi_complete()\\n                                      /* preempt */\\n\\n         * timeout/ signal wakes T1 *\\n\\n   futex_requeue_pi_wakeup_sync() // Q_REQUEUE_PI_LOCKED\\n   futex_hash_put()\\n  // back to userland, on stack futex_q is garbage\\n\\n                                      /* back */\\n                                     wake_up_state(q-\u003etask, TASK_NORMAL);\\n\\nIn this scenario futex_wait_requeue_pi() is able to leave without using\\nfutex_q::lock_ptr for synchronization.\\n\\nThis can be prevented by reading futex_q::task before updating the\\nfutex_q::requeue_state. A reference on the task_struct is not needed\\nbecause requeue_pi_wake_futex() is invoked with a spinlock_t held which\\nimplies a RCU read section.\\n\\nEven if T1 terminates immediately after, the task_struct will remain valid\\nduring T2\u0027s wake_up_state().  A READ_ONCE on futex_q::task before\\nfutex_requeue_pi_complete() is enough because it ensures that the variable\\nis read before the state is updated.\\n\\nRead futex_q::task before updating the requeue state, use it for the\\nfollowing wakeup.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/348736955ed6ca6e99ca24b93b1d3fbfe352c181\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/a170b9c0dde83312b8b58ccc91509c7c15711641\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/b549113738e8c751b613118032a724b772aa83f2\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/cb5d19a61274b51b49601214a87af573b43d60fa\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/d824b2dbdcfe3c390278dd9652ea526168ef6850\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.