{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2024-27058",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2024-27058"
  ],
  "published": "2024-05-01T13:00:38Z",
  "summary": "tmpfs: fix race on handling dquot rbtree",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ntmpfs: fix race on handling dquot rbtree\n\nA syzkaller reproducer found a race while attempting to remove dquot\ninformation from the rb tree.\n\nFetching the rb_tree root node must also be protected by the\ndqopt->dqio_sem, otherwise, giving the right timing, shmem_release_dquot()\nwill trigger a warning because it couldn't find a node in the tree, when\nthe real reason was the root node changing before the search starts:\n\nThread 1\t\t\t\tThread 2\n- shmem_release_dquot()\t\t\t- shmem_{acquire,release}_dquot()\n\n- fetch ROOT\t\t\t\t- Fetch ROOT\n\n\t\t\t\t\t- acquire dqio_sem\n- wait dqio_sem\n\n\t\t\t\t\t- do something, triger a tree rebalance\n\t\t\t\t\t- release dqio_sem\n\n- acquire dqio_sem\n- start searching for the node, but\n  from the wrong location, missing\n  the node, and triggering a warning.",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
    }
  ],
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.6.20-1+rpt1"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.6.20+rpt-rpi-2712",
            "binary_version": "1:6.6.20-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.20+rpt-rpi-v6",
            "binary_version": "1:6.6.20-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.20+rpt-rpi-v7",
            "binary_version": "1:6.6.20-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.20+rpt-rpi-v7l",
            "binary_version": "1:6.6.20-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.20+rpt-rpi-v8",
            "binary_version": "1:6.6.20-1+rpt1"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.6.20-1+rpt1": {
            "linux_commit": "6f16847710cc0502450788b9f12f0a14d3429668",
            "upstream_version": "6.6.20",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.6.24"
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2024-27058"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/c7077f43f30d817d10a9f8245e51576ac114b2f0"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/617d55b90e73c7b4aa2733ca6cc3f9b72d1124bb"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/f82f184874d2761ebaa60dccf577921a0dbb3810"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/0a69b6b3a026543bc215ccc866d0aea5579e6ce2"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T11:52:36Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 7.8,
      "cvss_v3_severity": "High",
      "scenario": "AV:L - The vulnerable code is reached through local filesystem operations (create/chgrp/unlink) on a quota-enabled tmpfs and through the quotactl syscall; there is no network-facing path.\nAC:L - The attacker controls both sides of the race \u2014 spawning concurrent threads that force rb-tree insertions/rotations via dquot_initialize()/dquot_transfer() while the quota release worker walks the tree from its stale root \u2014 and the window spans two blocking lock acquisitions (dq_lock, then dqio_sem) that the attacker can widen by contending dqio_sem; a syzkaller reproducer exists.\nPR:L - Only an unprivileged local user with write access to the quota-enabled tmpfs is needed, since shmem_acquire_dquot()/shmem_release_dquot() run on ordinary inode creation and chown/chgrp with no capability check; enabling quota at mount time is an administrator-side deployment precondition, not an attacker privilege.\nUI:N - The attacker triggers the race entirely from their own processes doing normal file operations; no action by any other user is required.\nS:U - The corruption and crash are confined to the kernel's own memory and the tmpfs quota subsystem, with no crossing into another security authority such as a hypervisor or IOMMU boundary.\nC:H - Because the root is fetched outside dqio_sem, the traversal can continue into a quota_id object that a concurrent shmem_release_dquot() already rb_erase()d and kfree()d, reading entry->id and following rb_left/rb_right out of freed kmalloc-64 memory that can be groomed with attacker data, and via Q_GETNEXTQUOTA that freed content is returned to userspace as a qid.\nI:H - After following stale/freed tree pointers the found: path stores four attacker-influenced 64-bit limit values into the located \"entry\", then rb_erase()s and kfree()s it, giving writes and a free against a reallocated heap object \u2014 heap corruption exploitable beyond a simple crash.\nA:H - The race reliably triggers WARN_ONCE() in shmem_release_dquot() (a panic under panic_on_warn) and returns -ENOENT with DQ_ACTIVE_B still set, so quota_release_workfn() restarts on the same dquot and can spin, stalling all quota releases and blocking flush_delayed_work()/quotaoff/umount; the unlocked info->dqi_priv deref in shmem_get_next_id() also NULL-derefs before its sb_has_quota_active() check."
    }
  }
}