ghsa-cvqf-8622-79m2
Vulnerability from github
Published
2024-08-21 09:31
Modified
2024-09-06 15:32
Severity ?
4.7 (Medium) - CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
Details

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

USB: gadgetfs: Fix race between mounting and unmounting

The syzbot fuzzer and Gerald Lee have identified a use-after-free bug in the gadgetfs driver, involving processes concurrently mounting and unmounting the gadgetfs filesystem. In particular, gadgetfs_fill_super() can race with gadgetfs_kill_sb(), causing the latter to deallocate the_device while the former is using it. The output from KASAN says, in part:

BUG: KASAN: use-after-free in instrument_atomic_read_write include/linux/instrumented.h:102 [inline] BUG: KASAN: use-after-free in atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:176 [inline] BUG: KASAN: use-after-free in __refcount_sub_and_test include/linux/refcount.h:272 [inline] BUG: KASAN: use-after-free in __refcount_dec_and_test include/linux/refcount.h:315 [inline] BUG: KASAN: use-after-free in refcount_dec_and_test include/linux/refcount.h:333 [inline] BUG: KASAN: use-after-free in put_dev drivers/usb/gadget/legacy/inode.c:159 [inline] BUG: KASAN: use-after-free in gadgetfs_kill_sb+0x33/0x100 drivers/usb/gadget/legacy/inode.c:2086 Write of size 4 at addr ffff8880276d7840 by task syz-executor126/18689

CPU: 0 PID: 18689 Comm: syz-executor126 Not tainted 6.1.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 Call Trace: ... atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:176 [inline] __refcount_sub_and_test include/linux/refcount.h:272 [inline] __refcount_dec_and_test include/linux/refcount.h:315 [inline] refcount_dec_and_test include/linux/refcount.h:333 [inline] put_dev drivers/usb/gadget/legacy/inode.c:159 [inline] gadgetfs_kill_sb+0x33/0x100 drivers/usb/gadget/legacy/inode.c:2086 deactivate_locked_super+0xa7/0xf0 fs/super.c:332 vfs_get_super fs/super.c:1190 [inline] get_tree_single+0xd0/0x160 fs/super.c:1207 vfs_get_tree+0x88/0x270 fs/super.c:1531 vfs_fsconfig_locked fs/fsopen.c:232 [inline]

The simplest solution is to ensure that gadgetfs_fill_super() and gadgetfs_kill_sb() are serialized by making them both acquire a new mutex.

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{
   affected: [],
   aliases: [
      "CVE-2022-48869",
   ],
   database_specific: {
      cwe_ids: [
         "CWE-416",
      ],
      github_reviewed: false,
      github_reviewed_at: null,
      nvd_published_at: "2024-08-21T07:15:04Z",
      severity: "MODERATE",
   },
   details: "In the Linux kernel, the following vulnerability has been resolved:\n\nUSB: gadgetfs: Fix race between mounting and unmounting\n\nThe syzbot fuzzer and Gerald Lee have identified a use-after-free bug\nin the gadgetfs driver, involving processes concurrently mounting and\nunmounting the gadgetfs filesystem.  In particular, gadgetfs_fill_super()\ncan race with gadgetfs_kill_sb(), causing the latter to deallocate\nthe_device while the former is using it.  The output from KASAN says,\nin part:\n\nBUG: KASAN: use-after-free in instrument_atomic_read_write include/linux/instrumented.h:102 [inline]\nBUG: KASAN: use-after-free in atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:176 [inline]\nBUG: KASAN: use-after-free in __refcount_sub_and_test include/linux/refcount.h:272 [inline]\nBUG: KASAN: use-after-free in __refcount_dec_and_test include/linux/refcount.h:315 [inline]\nBUG: KASAN: use-after-free in refcount_dec_and_test include/linux/refcount.h:333 [inline]\nBUG: KASAN: use-after-free in put_dev drivers/usb/gadget/legacy/inode.c:159 [inline]\nBUG: KASAN: use-after-free in gadgetfs_kill_sb+0x33/0x100 drivers/usb/gadget/legacy/inode.c:2086\nWrite of size 4 at addr ffff8880276d7840 by task syz-executor126/18689\n\nCPU: 0 PID: 18689 Comm: syz-executor126 Not tainted 6.1.0-syzkaller #0\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022\nCall Trace:\n <TASK>\n...\n atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:176 [inline]\n __refcount_sub_and_test include/linux/refcount.h:272 [inline]\n __refcount_dec_and_test include/linux/refcount.h:315 [inline]\n refcount_dec_and_test include/linux/refcount.h:333 [inline]\n put_dev drivers/usb/gadget/legacy/inode.c:159 [inline]\n gadgetfs_kill_sb+0x33/0x100 drivers/usb/gadget/legacy/inode.c:2086\n deactivate_locked_super+0xa7/0xf0 fs/super.c:332\n vfs_get_super fs/super.c:1190 [inline]\n get_tree_single+0xd0/0x160 fs/super.c:1207\n vfs_get_tree+0x88/0x270 fs/super.c:1531\n vfs_fsconfig_locked fs/fsopen.c:232 [inline]\n\nThe simplest solution is to ensure that gadgetfs_fill_super() and\ngadgetfs_kill_sb() are serialized by making them both acquire a new\nmutex.",
   id: "GHSA-cvqf-8622-79m2",
   modified: "2024-09-06T15:32:56Z",
   published: "2024-08-21T09:31:31Z",
   references: [
      {
         type: "ADVISORY",
         url: "https://nvd.nist.gov/vuln/detail/CVE-2022-48869",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/616fd34d017000ecf9097368b13d8a266f4920b3",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/856e4b5e53f21edbd15d275dde62228dd94fb2b4",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/9a39f4626b361ee7aa10fd990401c37ec3b466ae",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/a2e075f40122d8daf587db126c562a67abd69cf9",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/d18dcfe9860e842f394e37ba01ca9440ab2178f4",
      },
   ],
   schema_version: "1.4.0",
   severity: [
      {
         score: "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H",
         type: "CVSS_V3",
      },
   ],
}


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