title: btrfs: do not BUG_ON in link_to_fixup_dir
description: 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.
affected:
{
product: Linux
vendor: Linux
defaultStatus: unaffected
repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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
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
}
