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GHSA-3CVM-96RV-2MW4

Vulnerability from github – Published: 2025-03-27 18:31 – Updated: 2025-10-28 18:30
VLAI
Details

In the Linux kernel, the following vulnerability has been resolved:

fscache: Use wait_on_bit() to wait for the freeing of relinquished volume

The freeing of relinquished volume will wake up the pending volume acquisition by using wake_up_bit(), however it is mismatched with wait_var_event() used in fscache_wait_on_volume_collision() and it will never wake up the waiter in the wait-queue because these two functions operate on different wait-queues.

According to the implementation in fscache_wait_on_volume_collision(), if the wake-up of pending acquisition is delayed longer than 20 seconds (e.g., due to the delay of on-demand fd closing), the first wait_var_event_timeout() will timeout and the following wait_var_event() will hang forever as shown below:

FS-Cache: Potential volume collision new=00000024 old=00000022 ...... INFO: task mount:1148 blocked for more than 122 seconds. Not tainted 6.1.0-rc6+ #1 task:mount state:D stack:0 pid:1148 ppid:1 Call Trace: __schedule+0x2f6/0xb80 schedule+0x67/0xe0 fscache_wait_on_volume_collision.cold+0x80/0x82 __fscache_acquire_volume+0x40d/0x4e0 erofs_fscache_register_volume+0x51/0xe0 [erofs] erofs_fscache_register_fs+0x19c/0x240 [erofs] erofs_fc_fill_super+0x746/0xaf0 [erofs] vfs_get_super+0x7d/0x100 get_tree_nodev+0x16/0x20 erofs_fc_get_tree+0x20/0x30 [erofs] vfs_get_tree+0x24/0xb0 path_mount+0x2fa/0xa90 do_mount+0x7c/0xa0 __x64_sys_mount+0x8b/0xe0 do_syscall_64+0x30/0x60 entry_SYSCALL_64_after_hwframe+0x46/0xb0

Considering that wake_up_bit() is more selective, so fix it by using wait_on_bit() instead of wait_var_event() to wait for the freeing of relinquished volume. In addition because waitqueue_active() is used in wake_up_bit() and clear_bit() doesn't imply any memory barrier, use clear_and_wake_up_bit() to add the missing memory barrier between cursor->flags and waitqueue_active().

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2023-52982"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-03-27T17:15:45Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nfscache: Use wait_on_bit() to wait for the freeing of relinquished volume\n\nThe freeing of relinquished volume will wake up the pending volume\nacquisition by using wake_up_bit(), however it is mismatched with\nwait_var_event() used in fscache_wait_on_volume_collision() and it will\nnever wake up the waiter in the wait-queue because these two functions\noperate on different wait-queues.\n\nAccording to the implementation in fscache_wait_on_volume_collision(),\nif the wake-up of pending acquisition is delayed longer than 20 seconds\n(e.g., due to the delay of on-demand fd closing), the first\nwait_var_event_timeout() will timeout and the following wait_var_event()\nwill hang forever as shown below:\n\n FS-Cache: Potential volume collision new=00000024 old=00000022\n ......\n INFO: task mount:1148 blocked for more than 122 seconds.\n       Not tainted 6.1.0-rc6+ #1\n task:mount           state:D stack:0     pid:1148  ppid:1\n Call Trace:\n  \u003cTASK\u003e\n  __schedule+0x2f6/0xb80\n  schedule+0x67/0xe0\n  fscache_wait_on_volume_collision.cold+0x80/0x82\n  __fscache_acquire_volume+0x40d/0x4e0\n  erofs_fscache_register_volume+0x51/0xe0 [erofs]\n  erofs_fscache_register_fs+0x19c/0x240 [erofs]\n  erofs_fc_fill_super+0x746/0xaf0 [erofs]\n  vfs_get_super+0x7d/0x100\n  get_tree_nodev+0x16/0x20\n  erofs_fc_get_tree+0x20/0x30 [erofs]\n  vfs_get_tree+0x24/0xb0\n  path_mount+0x2fa/0xa90\n  do_mount+0x7c/0xa0\n  __x64_sys_mount+0x8b/0xe0\n  do_syscall_64+0x30/0x60\n  entry_SYSCALL_64_after_hwframe+0x46/0xb0\n\nConsidering that wake_up_bit() is more selective, so fix it by using\nwait_on_bit() instead of wait_var_event() to wait for the freeing of\nrelinquished volume. In addition because waitqueue_active() is used in\nwake_up_bit() and clear_bit() doesn\u0027t imply any memory barrier, use\nclear_and_wake_up_bit() to add the missing memory barrier between\ncursor-\u003eflags and waitqueue_active().",
  "id": "GHSA-3cvm-96rv-2mw4",
  "modified": "2025-10-28T18:30:24Z",
  "published": "2025-03-27T18:31:26Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-52982"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3be069f42a7b79d3149194f21cdf24bf23864cac"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8226e37d82f43657da34dd770e2b38f20242ada7"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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