{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "576215cffdefc1f0ceebffd87abb390926e6b037"
            },
            {
              "fixed": "37ccd48cf35f3c8b9f2ea961a7b486b91eb71a82"
            },
            {
              "fixed": "414259caf81a397563fc9baca9c0ef856c4a97cf"
            },
            {
              "fixed": "02bb1500f1479750e6557c8044f6a2d7e9d30c12"
            },
            {
              "fixed": "53b2314b26b6640a3657cc924de63a1a8f26ac4d"
            },
            {
              "fixed": "77449e453dfc006ad738dec55374c4cbc056fd39"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.5.0"
            },
            {
              "fixed": "6.6.128"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.75"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.14"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "6.19.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45895.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nquota: fix livelock between quotactl and freeze_super\n\nWhen a filesystem is frozen, quotactl_block() enters a retry loop\nwaiting for the filesystem to thaw. It acquires s_umount, checks the\nfreeze state, drops s_umount and uses sb_start_write() - sb_end_write()\npair to wait for the unfreeze.\n\nHowever, this retry loop can trigger a livelock issue, specifically on\nkernels with preemption disabled.\n\nThe mechanism is as follows:\n1. freeze_super() sets SB_FREEZE_WRITE and calls sb_wait_write().\n2. sb_wait_write() calls percpu_down_write(), which initiates\n   synchronize_rcu().\n3. Simultaneously, quotactl_block() spins in its retry loop, immediately\n   executing the sb_start_write() - sb_end_write() pair.\n4. Because the kernel is non-preemptible and the loop contains no\n   scheduling points, quotactl_block() never yields the CPU. This\n   prevents that CPU from reaching an RCU quiescent state.\n5. synchronize_rcu() in the freezer thread waits indefinitely for the\n   quotactl_block() CPU to report a quiescent state.\n6. quotactl_block() spins indefinitely waiting for the freezer to\n   advance, which it cannot do as it is blocked on the RCU sync.\n\nThis results in a hang of the freezer process and 100% CPU usage by the\nquota process.\n\nWhile this can occur intermittently on multi-core systems, it is\nreliably reproducing on a node with the following script, running both\nthe freezer and the quota toggle on the same CPU:\n\n  # mkfs.ext4 -O quota /dev/sda 2g \u0026\u0026 mkdir a_mount\n  # mount /dev/sda -o quota,usrquota,grpquota a_mount\n  # taskset -c 3 bash -c \"while true; do xfs_freeze -f a_mount; \\\n    xfs_freeze -u a_mount; done\" \u0026\n  # taskset -c 3 bash -c \"while true; do quotaon a_mount; \\\n    quotaoff a_mount; done\" \u0026\n\nAdding cond_resched() to the retry loop fixes the issue. It acts as an\nRCU quiescent state, allowing synchronize_rcu() in percpu_down_write()\nto complete.",
  "id": "CVE-2026-45895",
  "modified": "2026-07-08T05:39:14.811102166Z",
  "published": "2026-05-27T12:17:05.666Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/02bb1500f1479750e6557c8044f6a2d7e9d30c12"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/37ccd48cf35f3c8b9f2ea961a7b486b91eb71a82"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/414259caf81a397563fc9baca9c0ef856c4a97cf"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/53b2314b26b6640a3657cc924de63a1a8f26ac4d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/77449e453dfc006ad738dec55374c4cbc056fd39"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45895.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-45895"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.7.5",
  "summary": "quota: fix livelock between quotactl and freeze_super"
}