{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2"
            },
            {
              "fixed": "54626335ea4174ab2d9a183b511d825f6765e47b"
            },
            {
              "fixed": "897d6a7247739fb1528f98c575df4f2e5de7f994"
            },
            {
              "fixed": "32dbd5ce4be3a3ed7e00f8af18795cc84fc50a33"
            },
            {
              "fixed": "b5fa9e32fb6718f70c986ee14dd5d01b4846f331"
            },
            {
              "fixed": "1bee417678f1135e35b25a37734db46aa94258d2"
            },
            {
              "fixed": "20a93e397abe850c49b6fa0e8cc827b5f634a8f5"
            },
            {
              "fixed": "bfcc8e8d8a495bb34cae9e620adfb75fb13a3954"
            },
            {
              "fixed": "36c1b57b2ecf3c61ac93f5f07bd29b6f21e226ed"
            },
            {
              "fixed": "00633c4683828acd5256fa8d5163f440d74bbe71"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.6.12"
            },
            {
              "fixed": "5.10.259"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.11.0"
            },
            {
              "fixed": "5.15.210"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.16.0"
            },
            {
              "fixed": "6.1.176"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.2.0"
            },
            {
              "fixed": "6.6.143"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.94"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.36"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.0.13"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "7.1.0"
            },
            {
              "fixed": "7.1.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/52xxx/CVE-2026-52946.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nfs/fcntl: fix SOFTIRQ-unsafe lock order in fasync signaling\n\nA SOFTIRQ-safe to SOFTIRQ-unsafe lock order deadlock can occur in\nsend_sigio() and send_sigurg() when a process group receives a signal.\n\nWhen FASYNC is configured for a process group (PIDTYPE_PGID), both\nfunctions use read_lock(\u0026tasklist_lock) to traverse the task list.\nHowever, they are frequently called from softirq context:\n- send_sigio() via input_inject_event -\u003e kill_fasync\n- send_sigurg() via tcp_check_urg -\u003e sk_send_sigurg (NET_RX_SOFTIRQ)\n\nThe deadlock is caused by the rwlock writer fairness mechanism:\n1. CPU 0 (process context) holds read_lock(\u0026tasklist_lock) in do_wait().\n2. CPU 1 (process context) attempts write_lock(\u0026tasklist_lock) in\n   fork() or exit() and spins, which blocks all new readers.\n3. CPU 0 is interrupted by a softirq (e.g., TCP URG packet reception).\n4. The softirq calls send_sigurg() and attempts to acquire\n   read_lock(\u0026tasklist_lock), deadlocking because CPU 1 is waiting.\n\nSince PID hashing and do_each_pid_task() traversals are already\nRCU-protected, the read_lock on tasklist_lock is no longer strictly\nrequired for safe traversal. Fix this by replacing tasklist_lock with\nrcu_read_lock(), aligning the process group signaling path with the\nsingle-PID path. This also mitigates a potential remote denial of\nservice vector via TCP URG packets.\n\nLockdep splat:\n=====================================================\nWARNING: SOFTIRQ-safe -\u003e SOFTIRQ-unsafe lock order detected\n[...]\nChain exists of:\n  \u0026dev-\u003eevent_lock --\u003e \u0026f_owner-\u003elock --\u003e tasklist_lock\n\nPossible interrupt unsafe locking scenario:\n       CPU0                    CPU1\n       ----                    ----\n  lock(tasklist_lock);\n                           local_irq_disable();\n                           lock(\u0026dev-\u003eevent_lock);\n                           lock(\u0026f_owner-\u003elock);\n  \u003cInterrupt\u003e\n    lock(\u0026dev-\u003eevent_lock);\n\n*** DEADLOCK ***",
  "id": "CVE-2026-52946",
  "modified": "2026-07-08T05:36:33.253895603Z",
  "published": "2026-06-24T16:26:04.419Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/00633c4683828acd5256fa8d5163f440d74bbe71"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1bee417678f1135e35b25a37734db46aa94258d2"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/20a93e397abe850c49b6fa0e8cc827b5f634a8f5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/32dbd5ce4be3a3ed7e00f8af18795cc84fc50a33"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/36c1b57b2ecf3c61ac93f5f07bd29b6f21e226ed"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/54626335ea4174ab2d9a183b511d825f6765e47b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/897d6a7247739fb1528f98c575df4f2e5de7f994"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b5fa9e32fb6718f70c986ee14dd5d01b4846f331"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/bfcc8e8d8a495bb34cae9e620adfb75fb13a3954"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/52xxx/CVE-2026-52946.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-52946"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.7.5",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "fs/fcntl: fix SOFTIRQ-unsafe lock order in fasync signaling"
}