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| author | Theodore Ts'o <tytso@mit.edu> | 2022-05-17 20:27:55 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-06-09 11:21:23 +0300 |
| commit | cc5b09cb6dacd4b32640537929ab4ee8fb2b9e04 (patch) | |
| tree | 80f68d1e917834f6c2e62f089db9b737ac62ea83 /fs | |
| parent | 1b061af037646c9cdb0afd8a8d2f1e1c06285866 (diff) | |
| download | linux-cc5b09cb6dacd4b32640537929ab4ee8fb2b9e04.tar.xz | |
ext4: filter out EXT4_FC_REPLAY from on-disk superblock field s_state
commit c878bea3c9d724ddfa05a813f30de3d25a0ba83f upstream.
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.
Cc: stable@kernel.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20220420192312.1655305-1-phind.uet@gmail.com
Link: https://lore.kernel.org/r/20220517174028.942119-1-tytso@mit.edu
Reported-by: syzbot+c7358a3cd05ee786eb31@syzkaller.appspotmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/ext4/super.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 35d990adefc6..050108091f8a 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -4538,7 +4538,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) sbi->s_inodes_per_block; sbi->s_desc_per_block = blocksize / EXT4_DESC_SIZE(sb); sbi->s_sbh = bh; - sbi->s_mount_state = le16_to_cpu(es->s_state); + sbi->s_mount_state = le16_to_cpu(es->s_state) & ~EXT4_FC_REPLAY; sbi->s_addr_per_block_bits = ilog2(EXT4_ADDR_PER_BLOCK(sb)); sbi->s_desc_per_block_bits = ilog2(EXT4_DESC_PER_BLOCK(sb)); @@ -5998,7 +5998,8 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data) if (err) goto restore_opts; } - sbi->s_mount_state = le16_to_cpu(es->s_state); + sbi->s_mount_state = (le16_to_cpu(es->s_state) & + ~EXT4_FC_REPLAY); err = ext4_setup_super(sb, es, 0); if (err) |