CVE-2021-47145

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.