CVE-2021-47145 btrfs: do not BUG_ON in link_to_fixup_dir

2024-03-2509:07:42

Linux

github.com

linux kernel

btrfs

vulnerability

fix

panic

error handling

7 High

AI Score

Confidence

Low

0.0004 Low

EPSS

Percentile

13.0%

JSON

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

btrfs: do not BUG_ON in link_to_fixup_dir

While doing error injection testing I got the following panic

kernel BUG at fs/btrfs/tree-log.c:1862!
invalid opcode: 0000 [#1] SMP NOPTI
CPU: 1 PID: 7836 Comm: mount Not tainted 5.13.0-rc1+ #305
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014
RIP: 0010:link_to_fixup_dir+0xd5/0xe0
RSP: 0018:ffffb5800180fa30 EFLAGS: 00010216
RAX: fffffffffffffffb RBX: 00000000fffffffb RCX: ffff8f595287faf0
RDX: ffffb5800180fa37 RSI: ffff8f5954978800 RDI: 0000000000000000
RBP: ffff8f5953af9450 R08: 0000000000000019 R09: 0000000000000001
R10: 000151f408682970 R11: 0000000120021001 R12: ffff8f5954978800
R13: ffff8f595287faf0 R14: ffff8f5953c77dd0 R15: 0000000000000065
FS: 00007fc5284c8c40(0000) GS:ffff8f59bbd00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc5287f47c0 CR3: 000000011275e002 CR4: 0000000000370ee0
Call Trace:
replay_one_buffer+0x409/0x470
? btree_read_extent_buffer_pages+0xd0/0x110
walk_up_log_tree+0x157/0x1e0
walk_log_tree+0xa6/0x1d0
btrfs_recover_log_trees+0x1da/0x360
? replay_one_extent+0x7b0/0x7b0
open_ctree+0x1486/0x1720
btrfs_mount_root.cold+0x12/0xea
? __kmalloc_track_caller+0x12f/0x240
legacy_get_tree+0x24/0x40
vfs_get_tree+0x22/0xb0
vfs_kern_mount.part.0+0x71/0xb0
btrfs_mount+0x10d/0x380
? vfs_parse_fs_string+0x4d/0x90
legacy_get_tree+0x24/0x40
vfs_get_tree+0x22/0xb0
path_mount+0x433/0xa10
__x64_sys_mount+0xe3/0x120
do_syscall_64+0x3d/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xae

We can get -EIO or any number of legitimate errors from
btrfs_search_slot(), panicing here is not the appropriate response. The
error path for this code handles errors properly, simply return the
error.

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "fs/btrfs/tree-log.c"
    ],
    "versions": [
      {
        "version": "1da177e4c3f4",
        "lessThan": "76bfd8ac20be",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "1da177e4c3f4",
        "lessThan": "e934c4ee17b3",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "1da177e4c3f4",
        "lessThan": "0eaf383c6a4a",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "1da177e4c3f4",
        "lessThan": "6eccfb28f8dc",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "1da177e4c3f4",
        "lessThan": "0ed102453aa1",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "1da177e4c3f4",
        "lessThan": "7e13db503918",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "1da177e4c3f4",
        "lessThan": "b54544213358",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "1da177e4c3f4",
        "lessThan": "91df99a6eb50",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "fs/btrfs/tree-log.c"
    ],
    "versions": [
      {
        "version": "4.4.271",
        "lessThanOrEqual": "4.4.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "4.9.271",
        "lessThanOrEqual": "4.9.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "4.14.235",
        "lessThanOrEqual": "4.14.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "4.19.193",
        "lessThanOrEqual": "4.19.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.4.124",
        "lessThanOrEqual": "5.4.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.10.42",
        "lessThanOrEqual": "5.10.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.12.9",
        "lessThanOrEqual": "5.12.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.13",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]