CVE-2026-23393 (GCVE-0-2026-23393)

Vulnerability from cvelistv5 – Published: 2026-03-25 10:33 – Updated: 2026-05-11 22:06
VLAI
Title
bridge: cfm: Fix race condition in peer_mep deletion
Summary
In the Linux kernel, the following vulnerability has been resolved: bridge: cfm: Fix race condition in peer_mep deletion When a peer MEP is being deleted, cancel_delayed_work_sync() is called on ccm_rx_dwork before freeing. However, br_cfm_frame_rx() runs in softirq context under rcu_read_lock (without RTNL) and can re-schedule ccm_rx_dwork via ccm_rx_timer_start() between cancel_delayed_work_sync() returning and kfree_rcu() being called. The following is a simple race scenario: cpu0 cpu1 mep_delete_implementation() cancel_delayed_work_sync(ccm_rx_dwork); br_cfm_frame_rx() // peer_mep still in hlist if (peer_mep->ccm_defect) ccm_rx_timer_start() queue_delayed_work(ccm_rx_dwork) hlist_del_rcu(&peer_mep->head); kfree_rcu(peer_mep, rcu); ccm_rx_work_expired() // on freed peer_mep To prevent this, cancel_delayed_work_sync() is replaced with disable_delayed_work_sync() in both peer MEP deletion paths, so that subsequent queue_delayed_work() calls from br_cfm_frame_rx() are silently rejected. The cc_peer_disable() helper retains cancel_delayed_work_sync() because it is also used for the CC enable/disable toggle path where the work must remain re-schedulable.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: dc32cbb3dbd7da38c700d6e0fc6354df24920525 , < e89dbd2736a45f0507949af4748cbbf3ff793146 (git)
Affected: dc32cbb3dbd7da38c700d6e0fc6354df24920525 , < d8f35767bacb3c7769d470a41cf161e3f3c07e70 (git)
Affected: dc32cbb3dbd7da38c700d6e0fc6354df24920525 , < 1fd81151f65927fd9edb8ecd12ad45527dbbe5ab (git)
Affected: dc32cbb3dbd7da38c700d6e0fc6354df24920525 , < 3715a00855316066cdda69d43648336367422127 (git)
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Linux Linux Affected: 5.11
Unaffected: 0 , < 5.11 (semver)
Unaffected: 6.12.78 , ≤ 6.12.* (semver)
Unaffected: 6.18.20 , ≤ 6.18.* (semver)
Unaffected: 6.19.10 , ≤ 6.19.* (semver)
Unaffected: 7.0 , ≤ * (original_commit_for_fix)
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          "programFiles": [
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbridge: cfm: Fix race condition in peer_mep deletion\n\nWhen a peer MEP is being deleted, cancel_delayed_work_sync() is called\non ccm_rx_dwork before freeing. However, br_cfm_frame_rx() runs in\nsoftirq context under rcu_read_lock (without RTNL) and can re-schedule\nccm_rx_dwork via ccm_rx_timer_start() between cancel_delayed_work_sync()\nreturning and kfree_rcu() being called.\n\nThe following is a simple race scenario:\n\n           cpu0                                     cpu1\n\nmep_delete_implementation()\n  cancel_delayed_work_sync(ccm_rx_dwork);\n                                           br_cfm_frame_rx()\n                                             // peer_mep still in hlist\n                                             if (peer_mep-\u003eccm_defect)\n                                               ccm_rx_timer_start()\n                                                 queue_delayed_work(ccm_rx_dwork)\n  hlist_del_rcu(\u0026peer_mep-\u003ehead);\n  kfree_rcu(peer_mep, rcu);\n                                           ccm_rx_work_expired()\n                                             // on freed peer_mep\n\nTo prevent this, cancel_delayed_work_sync() is replaced with\ndisable_delayed_work_sync() in both peer MEP deletion paths, so\nthat subsequent queue_delayed_work() calls from br_cfm_frame_rx()\nare silently rejected.\n\nThe cc_peer_disable() helper retains cancel_delayed_work_sync()\nbecause it is also used for the CC enable/disable toggle path where\nthe work must remain re-schedulable."
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However, br_cfm_frame_rx() runs in\\nsoftirq context under rcu_read_lock (without RTNL) and can re-schedule\\nccm_rx_dwork via ccm_rx_timer_start() between cancel_delayed_work_sync()\\nreturning and kfree_rcu() being called.\\n\\nThe following is a simple race scenario:\\n\\n           cpu0                                     cpu1\\n\\nmep_delete_implementation()\\n  cancel_delayed_work_sync(ccm_rx_dwork);\\n                                           br_cfm_frame_rx()\\n                                             // peer_mep still in hlist\\n                                             if (peer_mep-\u003eccm_defect)\\n                                               ccm_rx_timer_start()\\n                                                 queue_delayed_work(ccm_rx_dwork)\\n  hlist_del_rcu(\u0026peer_mep-\u003ehead);\\n  kfree_rcu(peer_mep, rcu);\\n                                           ccm_rx_work_expired()\\n                                             // on freed peer_mep\\n\\nTo prevent this, cancel_delayed_work_sync() is replaced with\\ndisable_delayed_work_sync() in both peer MEP deletion paths, so\\nthat subsequent queue_delayed_work() calls from br_cfm_frame_rx()\\nare silently rejected.\\n\\nThe cc_peer_disable() helper retains cancel_delayed_work_sync()\\nbecause it is also used for the CC enable/disable toggle path where\\nthe work must remain re-schedulable.\"},{\"lang\":\"es\",\"value\":\"En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad:\\n\\nbridge: cfm: Correcci\u00f3n de condici\u00f3n de carrera en la eliminaci\u00f3n de peer_mep\\n\\nCuando se est\u00e1 eliminando un MEP par, se llama a cancel_delayed_work_sync() en ccm_rx_dwork antes de la liberaci\u00f3n. Sin embargo, br_cfm_frame_rx() se ejecuta en contexto de softirq bajo rcu_read_lock (sin RTNL) y puede reprogramar ccm_rx_dwork a trav\u00e9s de ccm_rx_timer_start() entre el retorno de cancel_delayed_work_sync() y la llamada a kfree_rcu().\\n\\nEl siguiente es un escenario de condici\u00f3n de carrera simple:\\n\\n           cpu0                                     cpu1\\n\\nmep_delete_implementation()\\n  cancel_delayed_work_sync(ccm_rx_dwork);\\n                                           br_cfm_frame_rx()\\n                                             // peer_mep todav\u00eda en hlist\\n                                             if (peer_mep-\u0026gt;ccm_defect)\\n                                               ccm_rx_timer_start()\\n                                                 queue_delayed_work(ccm_rx_dwork)\\n  hlist_del_rcu(\u0026amp;peer_mep-\u0026gt;head);\\n  kfree_rcu(peer_mep, rcu);\\n                                           ccm_rx_work_expired()\\n                                             // en peer_mep liberado\\n\\nPara evitar esto, cancel_delayed_work_sync() se reemplaza por disable_delayed_work_sync() en ambas rutas de eliminaci\u00f3n de MEP par, de modo que las llamadas posteriores a queue_delayed_work() desde br_cfm_frame_rx() sean rechazadas silenciosamente.\\n\\nLa funci\u00f3n auxiliar cc_peer_disable() mantiene cancel_delayed_work_sync() porque tambi\u00e9n se utiliza para la ruta de alternancia de habilitaci\u00f3n/deshabilitaci\u00f3n de CC donde el trabajo debe permanecer reprogramable.\"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":7.8,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":5.9}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-362\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.11.1\",\"versionEndExcluding\":\"6.12.78\",\"matchCriteriaId\":\"0618528B-8039-4E87-8695-397AE7D4B4E5\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.13\",\"versionEndExcluding\":\"6.18.20\",\"matchCriteriaId\":\"E5571059-6552-48E7-9BEF-3E358C387171\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.19\",\"versionEndExcluding\":\"6.19.10\",\"matchCriteriaId\":\"96D34333-38BE-4414-9E79-6EB764329581\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:5.11:-:*:*:*:*:*:*\",\"matchCriteriaId\":\"7AD3510E-E8FA-47F3-9AD5-D8EA4A2719D1\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*\",\"matchCriteriaId\":\"F253B622-8837-4245-BCE5-A7BF8FC76A16\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*\",\"matchCriteriaId\":\"4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*\",\"matchCriteriaId\":\"F666C8D8-6538-46D4-B318-87610DE64C34\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*\",\"matchCriteriaId\":\"02259FDA-961B-47BC-AE7F-93D7EC6E90C2\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*\",\"matchCriteriaId\":\"58A9FEFF-C040-420D-8F0A-BFDAAA1DF258\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*\",\"matchCriteriaId\":\"1D2315C0-D46F-4F85-9754-F9E5E11374A6\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:*\",\"matchCriteriaId\":\"512EE3A8-A590-4501-9A94-5D4B268D6138\"}]}]}],\"references\":[{\"url\":\"https://git.kernel.org/stable/c/1fd81151f65927fd9edb8ecd12ad45527dbbe5ab\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/3715a00855316066cdda69d43648336367422127\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/d8f35767bacb3c7769d470a41cf161e3f3c07e70\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/e89dbd2736a45f0507949af4748cbbf3ff793146\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]}]}}"
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}


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  • 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.
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  • 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.


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