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| author | Theodore Ts'o <tytso@mit.edu> | 2022-05-17 20:27:55 +0300 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2022-05-24 22:33:58 +0300 |
| commit | c878bea3c9d724ddfa05a813f30de3d25a0ba83f (patch) | |
| tree | e5f9d22f52390a38738844e24d49b6f0e617ad3a /fs/ext4 | |
| parent | ef09ed5d37b84d18562b30cf7253e57062d0db05 (diff) | |
| download | linux-c878bea3c9d724ddfa05a813f30de3d25a0ba83f.tar.xz | |
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.
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
Diffstat (limited to 'fs/ext4')
| -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 7f6cd2473163..9cbb22045379 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -4770,7 +4770,7 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb) 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)); @@ -6333,7 +6333,8 @@ static int __ext4_remount(struct fs_context *fc, struct super_block *sb) 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) |