CVE-2026-31598 (GCVE-0-2026-31598)
Vulnerability from cvelistv5
Published
2026-04-24 14:42
Modified
2026-08-05 12:23
Severity ?
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: ocfs2: fix possible deadlock between unlink and dio_end_io_write ocfs2_unlink takes orphan dir inode_lock first and then ip_alloc_sem, while in ocfs2_dio_end_io_write, it acquires these locks in reverse order. This creates an ABBA lock ordering violation on lock classes ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE] and ocfs2_file_ip_alloc_sem_key. Lock Chain #0 (orphan dir inode_lock -> ip_alloc_sem): ocfs2_unlink ocfs2_prepare_orphan_dir ocfs2_lookup_lock_orphan_dir inode_lock(orphan_dir_inode) <- lock A __ocfs2_prepare_orphan_dir ocfs2_prepare_dir_for_insert ocfs2_extend_dir ocfs2_expand_inline_dir down_write(&oi->ip_alloc_sem) <- Lock B Lock Chain #1 (ip_alloc_sem -> orphan dir inode_lock): ocfs2_dio_end_io_write down_write(&oi->ip_alloc_sem) <- Lock B ocfs2_del_inode_from_orphan() inode_lock(orphan_dir_inode) <- Lock A Deadlock Scenario: CPU0 (unlink) CPU1 (dio_end_io_write) ------ ------ inode_lock(orphan_dir_inode) down_write(ip_alloc_sem) down_write(ip_alloc_sem) inode_lock(orphan_dir_inode) Since ip_alloc_sem is to protect allocation changes, which is unrelated with operations in ocfs2_del_inode_from_orphan. So move ocfs2_del_inode_from_orphan out of ip_alloc_sem to fix the deadlock.
References
Impacted products
Vendor Product Version
Linux Linux Version: a86a72a4a4e0ec109a98e2737948864ed6794bf7
Version: a86a72a4a4e0ec109a98e2737948864ed6794bf7
Version: a86a72a4a4e0ec109a98e2737948864ed6794bf7
Version: a86a72a4a4e0ec109a98e2737948864ed6794bf7
Version: a86a72a4a4e0ec109a98e2737948864ed6794bf7
Version: a86a72a4a4e0ec109a98e2737948864ed6794bf7
Version: a86a72a4a4e0ec109a98e2737948864ed6794bf7
Version: a86a72a4a4e0ec109a98e2737948864ed6794bf7
Version: a86a72a4a4e0ec109a98e2737948864ed6794bf7
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{
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          "programFiles": [
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nocfs2: fix possible deadlock between unlink and dio_end_io_write\n\nocfs2_unlink takes orphan dir inode_lock first and then ip_alloc_sem,\nwhile in ocfs2_dio_end_io_write, it acquires these locks in reverse order.\nThis creates an ABBA lock ordering violation on lock classes\nocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE] and\nocfs2_file_ip_alloc_sem_key.\n\nLock Chain #0 (orphan dir inode_lock -\u003e ip_alloc_sem):\nocfs2_unlink\n  ocfs2_prepare_orphan_dir\n    ocfs2_lookup_lock_orphan_dir\n      inode_lock(orphan_dir_inode) \u003c- lock A\n    __ocfs2_prepare_orphan_dir\n      ocfs2_prepare_dir_for_insert\n        ocfs2_extend_dir\n\t  ocfs2_expand_inline_dir\n\t    down_write(\u0026oi-\u003eip_alloc_sem) \u003c- Lock B\n\nLock Chain #1 (ip_alloc_sem -\u003e orphan dir inode_lock):\nocfs2_dio_end_io_write\n  down_write(\u0026oi-\u003eip_alloc_sem) \u003c- Lock B\n  ocfs2_del_inode_from_orphan()\n    inode_lock(orphan_dir_inode) \u003c- Lock A\n\nDeadlock Scenario:\n  CPU0 (unlink)                     CPU1 (dio_end_io_write)\n  ------                            ------\n  inode_lock(orphan_dir_inode)\n                                    down_write(ip_alloc_sem)\n  down_write(ip_alloc_sem)\n                                    inode_lock(orphan_dir_inode)\n\nSince ip_alloc_sem is to protect allocation changes, which is unrelated\nwith operations in ocfs2_del_inode_from_orphan.  So move\nocfs2_del_inode_from_orphan out of ip_alloc_sem to fix the deadlock."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - Although the core bug is in ocfs2 filesystem code, ocfs2 is exportable and nfsd can issue direct writes with IOCB_DIRECT while remote REMOVE operations reach vfs_unlink, making the vulnerable lock chains reachable over the network on a writable exported ocfs2 volume.\nAC:L - The bug is an ABBA deadlock where the attacker can drive both sides with concurrent extending direct writes and unlink/remove operations. Once the target deployment exposes those operations, winning the race is attacker-controlled.\nPR:N - A remote NFS client can trigger the operations through an exported writable share without kernel capabilities on the target. In permissive or anonymous export scenarios, no prior authenticated privileges are required.\nUI:N - No victim user action is required after the vulnerable service/filesystem is available. The attacker can send the write and remove operations directly.\nS:U - The impact remains within the same kernel/filesystem security authority. There is no VM escape, sandbox boundary crossing, or separate security scope.\nC:N - The issue is a lock-ordering deadlock, not memory corruption or information disclosure. It does not provide a read primitive or leak data.\nI:N - The vulnerable behavior does not corrupt memory or allow unauthorized data modification. It only causes threads to block on locks.\nA:H - The deadlock can permanently hang ocfs2 operations and affected kernel worker/syscall contexts. A kernel/filesystem hang is a high availability impact."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:23:42.417Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/297d8d7bb6a2bf133d3a3636edbdf94101cbd719"
        },
        {
          "url": "https://git.kernel.org/stable/c/32630dee18c6bb2175c8a865a474749492eaf19c"
        },
        {
          "url": "https://git.kernel.org/stable/c/93f35419eb84d58820040642cb6e7528fe4aba7a"
        },
        {
          "url": "https://git.kernel.org/stable/c/4b80b5a838a32437f2cae0662578bac216a2c51a"
        },
        {
          "url": "https://git.kernel.org/stable/c/2b884d52273c60c298bd570163e8053657bbaff6"
        },
        {
          "url": "https://git.kernel.org/stable/c/bc0fb5c7d54c78be43a536df0e20dee32adb27d3"
        },
        {
          "url": "https://git.kernel.org/stable/c/f9fb1a7b635849322e1d7b7b6b26389778ec8e82"
        },
        {
          "url": "https://git.kernel.org/stable/c/e049f7a9bd80b7319590789ea5e1c523d6339d91"
        },
        {
          "url": "https://git.kernel.org/stable/c/b02da26a992db0c0e2559acbda0fc48d4a2fd337"
        }
      ],
      "title": "ocfs2: fix possible deadlock between unlink and dio_end_io_write",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-31598",
    "datePublished": "2026-04-24T14:42:23.304Z",
    "dateReserved": "2026-03-09T15:48:24.121Z",
    "dateUpdated": "2026-08-05T12:23:42.417Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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