CVE-2021-47406

In the Linux kernel, the following vulnerability has been resolved: ext4:
add error checking to ext4_ext_replay_set_iblocks() If the call to
ext4_map_blocks() fails due to an corrupted file system,
ext4_ext_replay_set_iblocks() can get stuck in an infinite loop. This could
be reproduced by running generic/526 with a file system that has
inline_data and fast_commit enabled. The system will repeatedly log to the
console: EXT4-fs warning (device dm-3): ext4_block_to_path:105: block
1074800922 > max in inode 131076 and the stack that it gets stuck in is:
ext4_block_to_path+0xe3/0x130 ext4_ind_map_blocks+0x93/0x690
ext4_map_blocks+0x100/0x660 skip_hole+0x47/0x70
ext4_ext_replay_set_iblocks+0x223/0x440 ext4_fc_replay_inode+0x29e/0x3b0
ext4_fc_replay+0x278/0x550 do_one_pass+0x646/0xc10
jbd2_journal_recover+0x14a/0x270 jbd2_journal_load+0xc4/0x150
ext4_load_journal+0x1f3/0x490 ext4_fill_super+0x22d4/0x2c00 With this
patch, generic/526 still fails, but system is no longer locking up in a
tight loop. It’s likely the root casue is that fast_commit replay is
corrupting file systems with inline_data, and we probably need to add
better error handling in the fast commit replay code path beyond what is
done here, which essentially just breaks the infinite loop without
reporting the to the higher levels of the code.