ghsa-9x65-m9rh-pqxf
Vulnerability from github
Published
2024-04-02 09:30
Modified
2024-04-02 09:30
Details

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

bcachefs: grab s_umount only if snapshotting

When I was testing mongodb over bcachefs with compression, there is a lockdep warning when snapshotting mongodb data volume.

$ cat test.sh prog=bcachefs

$prog subvolume create /mnt/data $prog subvolume create /mnt/data/snapshots

while true;do $prog subvolume snapshot /mnt/data /mnt/data/snapshots/$(date +%s) sleep 1s done

$ cat /etc/mongodb.conf systemLog: destination: file logAppend: true path: /mnt/data/mongod.log

storage: dbPath: /mnt/data/

lockdep reports: [ 3437.452330] ====================================================== [ 3437.452750] WARNING: possible circular locking dependency detected [ 3437.453168] 6.7.0-rc7-custom+ #85 Tainted: G E [ 3437.453562] ------------------------------------------------------ [ 3437.453981] bcachefs/35533 is trying to acquire lock: [ 3437.454325] ffffa0a02b2b1418 (sb_writers#10){.+.+}-{0:0}, at: filename_create+0x62/0x190 [ 3437.454875] but task is already holding lock: [ 3437.455268] ffffa0a02b2b10e0 (&type->s_umount_key#48){.+.+}-{3:3}, at: bch2_fs_file_ioctl+0x232/0xc90 [bcachefs] [ 3437.456009] which lock already depends on the new lock.

[ 3437.456553] the existing dependency chain (in reverse order) is: [ 3437.457054] -> #3 (&type->s_umount_key#48){.+.+}-{3:3}: [ 3437.457507] down_read+0x3e/0x170 [ 3437.457772] bch2_fs_file_ioctl+0x232/0xc90 [bcachefs] [ 3437.458206] __x64_sys_ioctl+0x93/0xd0 [ 3437.458498] do_syscall_64+0x42/0xf0 [ 3437.458779] entry_SYSCALL_64_after_hwframe+0x6e/0x76 [ 3437.459155] -> #2 (&c->snapshot_create_lock){++++}-{3:3}: [ 3437.459615] down_read+0x3e/0x170 [ 3437.459878] bch2_truncate+0x82/0x110 [bcachefs] [ 3437.460276] bchfs_truncate+0x254/0x3c0 [bcachefs] [ 3437.460686] notify_change+0x1f1/0x4a0 [ 3437.461283] do_truncate+0x7f/0xd0 [ 3437.461555] path_openat+0xa57/0xce0 [ 3437.461836] do_filp_open+0xb4/0x160 [ 3437.462116] do_sys_openat2+0x91/0xc0 [ 3437.462402] __x64_sys_openat+0x53/0xa0 [ 3437.462701] do_syscall_64+0x42/0xf0 [ 3437.462982] entry_SYSCALL_64_after_hwframe+0x6e/0x76 [ 3437.463359] -> #1 (&sb->s_type->i_mutex_key#15){+.+.}-{3:3}: [ 3437.463843] down_write+0x3b/0xc0 [ 3437.464223] bch2_write_iter+0x5b/0xcc0 [bcachefs] [ 3437.464493] vfs_write+0x21b/0x4c0 [ 3437.464653] ksys_write+0x69/0xf0 [ 3437.464839] do_syscall_64+0x42/0xf0 [ 3437.465009] entry_SYSCALL_64_after_hwframe+0x6e/0x76 [ 3437.465231] -> #0 (sb_writers#10){.+.+}-{0:0}: [ 3437.465471] __lock_acquire+0x1455/0x21b0 [ 3437.465656] lock_acquire+0xc6/0x2b0 [ 3437.465822] mnt_want_write+0x46/0x1a0 [ 3437.465996] filename_create+0x62/0x190 [ 3437.466175] user_path_create+0x2d/0x50 [ 3437.466352] bch2_fs_file_ioctl+0x2ec/0xc90 [bcachefs] [ 3437.466617] __x64_sys_ioctl+0x93/0xd0 [ 3437.466791] do_syscall_64+0x42/0xf0 [ 3437.466957] entry_SYSCALL_64_after_hwframe+0x6e/0x76 [ 3437.467180] other info that might help us debug this:

[ 3437.469670] 2 locks held by bcachefs/35533: other info that might help us debug this:

[ 3437.467507] Chain exists of: sb_writers#10 --> &c->snapshot_create_lock --> &type->s_umount_key#48

[ 3437.467979] Possible unsafe locking scenario:

[ 3437.468223] CPU0 CPU1 [ 3437.468405] ---- ---- [ 3437.468585] rlock(&type->s_umount_key#48); [ 3437.468758] lock(&c->snapshot_create_lock); [ 3437.469030] lock(&type->s_umount_key#48); [ 3437.469291] rlock(sb_writers#10); [ 3437.469434] *** DEADLOCK ***

[ 3437.469 ---truncated---

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{
  "affected": [],
  "aliases": [
    "CVE-2024-26658"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-04-02T07:15:42Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbcachefs: grab s_umount only if snapshotting\n\nWhen I was testing mongodb over bcachefs with compression,\nthere is a lockdep warning when snapshotting mongodb data volume.\n\n$ cat test.sh\nprog=bcachefs\n\n$prog subvolume create /mnt/data\n$prog subvolume create /mnt/data/snapshots\n\nwhile true;do\n    $prog subvolume snapshot /mnt/data /mnt/data/snapshots/$(date +%s)\n    sleep 1s\ndone\n\n$ cat /etc/mongodb.conf\nsystemLog:\n  destination: file\n  logAppend: true\n  path: /mnt/data/mongod.log\n\nstorage:\n  dbPath: /mnt/data/\n\nlockdep reports:\n[ 3437.452330] ======================================================\n[ 3437.452750] WARNING: possible circular locking dependency detected\n[ 3437.453168] 6.7.0-rc7-custom+ #85 Tainted: G            E\n[ 3437.453562] ------------------------------------------------------\n[ 3437.453981] bcachefs/35533 is trying to acquire lock:\n[ 3437.454325] ffffa0a02b2b1418 (sb_writers#10){.+.+}-{0:0}, at: filename_create+0x62/0x190\n[ 3437.454875]\n               but task is already holding lock:\n[ 3437.455268] ffffa0a02b2b10e0 (\u0026type-\u003es_umount_key#48){.+.+}-{3:3}, at: bch2_fs_file_ioctl+0x232/0xc90 [bcachefs]\n[ 3437.456009]\n               which lock already depends on the new lock.\n\n[ 3437.456553]\n               the existing dependency chain (in reverse order) is:\n[ 3437.457054]\n               -\u003e #3 (\u0026type-\u003es_umount_key#48){.+.+}-{3:3}:\n[ 3437.457507]        down_read+0x3e/0x170\n[ 3437.457772]        bch2_fs_file_ioctl+0x232/0xc90 [bcachefs]\n[ 3437.458206]        __x64_sys_ioctl+0x93/0xd0\n[ 3437.458498]        do_syscall_64+0x42/0xf0\n[ 3437.458779]        entry_SYSCALL_64_after_hwframe+0x6e/0x76\n[ 3437.459155]\n               -\u003e #2 (\u0026c-\u003esnapshot_create_lock){++++}-{3:3}:\n[ 3437.459615]        down_read+0x3e/0x170\n[ 3437.459878]        bch2_truncate+0x82/0x110 [bcachefs]\n[ 3437.460276]        bchfs_truncate+0x254/0x3c0 [bcachefs]\n[ 3437.460686]        notify_change+0x1f1/0x4a0\n[ 3437.461283]        do_truncate+0x7f/0xd0\n[ 3437.461555]        path_openat+0xa57/0xce0\n[ 3437.461836]        do_filp_open+0xb4/0x160\n[ 3437.462116]        do_sys_openat2+0x91/0xc0\n[ 3437.462402]        __x64_sys_openat+0x53/0xa0\n[ 3437.462701]        do_syscall_64+0x42/0xf0\n[ 3437.462982]        entry_SYSCALL_64_after_hwframe+0x6e/0x76\n[ 3437.463359]\n               -\u003e #1 (\u0026sb-\u003es_type-\u003ei_mutex_key#15){+.+.}-{3:3}:\n[ 3437.463843]        down_write+0x3b/0xc0\n[ 3437.464223]        bch2_write_iter+0x5b/0xcc0 [bcachefs]\n[ 3437.464493]        vfs_write+0x21b/0x4c0\n[ 3437.464653]        ksys_write+0x69/0xf0\n[ 3437.464839]        do_syscall_64+0x42/0xf0\n[ 3437.465009]        entry_SYSCALL_64_after_hwframe+0x6e/0x76\n[ 3437.465231]\n               -\u003e #0 (sb_writers#10){.+.+}-{0:0}:\n[ 3437.465471]        __lock_acquire+0x1455/0x21b0\n[ 3437.465656]        lock_acquire+0xc6/0x2b0\n[ 3437.465822]        mnt_want_write+0x46/0x1a0\n[ 3437.465996]        filename_create+0x62/0x190\n[ 3437.466175]        user_path_create+0x2d/0x50\n[ 3437.466352]        bch2_fs_file_ioctl+0x2ec/0xc90 [bcachefs]\n[ 3437.466617]        __x64_sys_ioctl+0x93/0xd0\n[ 3437.466791]        do_syscall_64+0x42/0xf0\n[ 3437.466957]        entry_SYSCALL_64_after_hwframe+0x6e/0x76\n[ 3437.467180]\n               other info that might help us debug this:\n\n[ 3437.469670] 2 locks held by bcachefs/35533:\n               other info that might help us debug this:\n\n[ 3437.467507] Chain exists of:\n                 sb_writers#10 --\u003e \u0026c-\u003esnapshot_create_lock --\u003e \u0026type-\u003es_umount_key#48\n\n[ 3437.467979]  Possible unsafe locking scenario:\n\n[ 3437.468223]        CPU0                    CPU1\n[ 3437.468405]        ----                    ----\n[ 3437.468585]   rlock(\u0026type-\u003es_umount_key#48);\n[ 3437.468758]                                lock(\u0026c-\u003esnapshot_create_lock);\n[ 3437.469030]                                lock(\u0026type-\u003es_umount_key#48);\n[ 3437.469291]   rlock(sb_writers#10);\n[ 3437.469434]\n                *** DEADLOCK ***\n\n[ 3437.469\n---truncated---",
  "id": "GHSA-9x65-m9rh-pqxf",
  "modified": "2024-04-02T09:30:40Z",
  "published": "2024-04-02T09:30:40Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-26658"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2acc59dd88d27ad69b66ded80df16c042b04eeec"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5b41d3fd04c6757b9c2a60a0c5b2609cae9999df"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


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