CVE-2022-49348

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

ext4: filter out EXT4_FC_REPLAY from on-disk superblock field s_state

The EXT4_FC_REPLAY bit in sbi->s_mount_state is used to indicate that
we are in the middle of replay the fast commit journal.  This was
actually a mistake, since the sbi->s_mount_info is initialized from
es->s_state.  Arguably s_mount_state is misleadingly named, but the
name is historical --- s_mount_state and s_state dates back to ext2.

What should have been used is the ext4_{set,clear,test}_mount_flag()
inline functions, which sets EXT4_MF_* bits in sbi->s_mount_flags.

The problem with using EXT4_FC_REPLAY is that a maliciously corrupted
superblock could result in EXT4_FC_REPLAY getting set in
s_mount_state.  This bypasses some sanity checks, and this can trigger
a BUG() in ext4_es_cache_extent().  As a easy-to-backport-fix, filter
out the EXT4_FC_REPLAY bit for now.  We should eventually transition
away from EXT4_FC_REPLAY to something like EXT4_MF_REPLAY.