ghsa-3gqx-rv8x-9m5c
Vulnerability from github
Published
2024-12-27 15:31
Modified
2025-02-11 18:31
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Details

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

f2fs: fix race in concurrent f2fs_stop_gc_thread

In my test case, concurrent calls to f2fs shutdown report the following stack trace:

Oops: general protection fault, probably for non-canonical address 0xc6cfff63bb5513fc: 0000 [#1] PREEMPT SMP PTI CPU: 0 UID: 0 PID: 678 Comm: f2fs_rep_shutdo Not tainted 6.12.0-rc5-next-20241029-g6fb2fa9805c5-dirty #85 Call Trace: ? show_regs+0x8b/0xa0 ? __die_body+0x26/0xa0 ? die_addr+0x54/0x90 ? exc_general_protection+0x24b/0x5c0 ? asm_exc_general_protection+0x26/0x30 ? kthread_stop+0x46/0x390 f2fs_stop_gc_thread+0x6c/0x110 f2fs_do_shutdown+0x309/0x3a0 f2fs_ioc_shutdown+0x150/0x1c0 __f2fs_ioctl+0xffd/0x2ac0 f2fs_ioctl+0x76/0xe0 vfs_ioctl+0x23/0x60 __x64_sys_ioctl+0xce/0xf0 x64_sys_call+0x2b1b/0x4540 do_syscall_64+0xa7/0x240 entry_SYSCALL_64_after_hwframe+0x76/0x7e

The root cause is a race condition in f2fs_stop_gc_thread() called from different f2fs shutdown paths:

[CPU0] [CPU1] ---------------------- ----------------------- f2fs_stop_gc_thread f2fs_stop_gc_thread gc_th = sbi->gc_thread gc_th = sbi->gc_thread kfree(gc_th) sbi->gc_thread = NULL < gc_th != NULL > kthread_stop(gc_th->f2fs_gc_task) //UAF

The commit c7f114d864ac ("f2fs: fix to avoid use-after-free in f2fs_stop_gc_thread()") attempted to fix this issue by using a read semaphore to prevent races between shutdown and remount threads, but it fails to prevent all race conditions.

Fix it by converting to write lock of s_umount in f2fs_do_shutdown().

Show details on source website

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{
   affected: [],
   aliases: [
      "CVE-2024-53218",
   ],
   database_specific: {
      cwe_ids: [
         "CWE-416",
      ],
      github_reviewed: false,
      github_reviewed_at: null,
      nvd_published_at: "2024-12-27T14:15:29Z",
      severity: "HIGH",
   },
   details: "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix race in concurrent f2fs_stop_gc_thread\n\nIn my test case, concurrent calls to f2fs shutdown report the following\nstack trace:\n\n Oops: general protection fault, probably for non-canonical address 0xc6cfff63bb5513fc: 0000 [#1] PREEMPT SMP PTI\n CPU: 0 UID: 0 PID: 678 Comm: f2fs_rep_shutdo Not tainted 6.12.0-rc5-next-20241029-g6fb2fa9805c5-dirty #85\n Call Trace:\n  <TASK>\n  ? show_regs+0x8b/0xa0\n  ? __die_body+0x26/0xa0\n  ? die_addr+0x54/0x90\n  ? exc_general_protection+0x24b/0x5c0\n  ? asm_exc_general_protection+0x26/0x30\n  ? kthread_stop+0x46/0x390\n  f2fs_stop_gc_thread+0x6c/0x110\n  f2fs_do_shutdown+0x309/0x3a0\n  f2fs_ioc_shutdown+0x150/0x1c0\n  __f2fs_ioctl+0xffd/0x2ac0\n  f2fs_ioctl+0x76/0xe0\n  vfs_ioctl+0x23/0x60\n  __x64_sys_ioctl+0xce/0xf0\n  x64_sys_call+0x2b1b/0x4540\n  do_syscall_64+0xa7/0x240\n  entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nThe root cause is a race condition in f2fs_stop_gc_thread() called from\ndifferent f2fs shutdown paths:\n\n  [CPU0]                       [CPU1]\n  ----------------------       -----------------------\n  f2fs_stop_gc_thread          f2fs_stop_gc_thread\n                                 gc_th = sbi->gc_thread\n    gc_th = sbi->gc_thread\n    kfree(gc_th)\n    sbi->gc_thread = NULL\n                                 < gc_th != NULL >\n                                 kthread_stop(gc_th->f2fs_gc_task) //UAF\n\nThe commit c7f114d864ac (\"f2fs: fix to avoid use-after-free in\nf2fs_stop_gc_thread()\") attempted to fix this issue by using a read\nsemaphore to prevent races between shutdown and remount threads, but\nit fails to prevent all race conditions.\n\nFix it by converting to write lock of s_umount in f2fs_do_shutdown().",
   id: "GHSA-3gqx-rv8x-9m5c",
   modified: "2025-02-11T18:31:22Z",
   published: "2024-12-27T15:31:52Z",
   references: [
      {
         type: "ADVISORY",
         url: "https://nvd.nist.gov/vuln/detail/CVE-2024-53218",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/60457ed6c67625c87861f96912b4179dc2293896",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/794fa8792d4eacac191f1cbcc2e81b7369e4662a",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/7b0033dbc48340a1c1c3f12448ba17d6587ca092",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/c631207897a9b3d41167ceca58e07f8f94720e42",
      },
   ],
   schema_version: "1.4.0",
   severity: [
      {
         score: "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
         type: "CVSS_V3",
      },
   ],
}


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