ext4: validate external journal superblock checksum
If the external journal device has metadata_csum enabled, verify
that the superblock checksum matches the block before we try to
mount.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index fb219b9..2632017 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -4414,6 +4414,15 @@
goto out_bdev;
}
+ if ((le32_to_cpu(es->s_feature_ro_compat) &
+ EXT4_FEATURE_RO_COMPAT_METADATA_CSUM) &&
+ es->s_checksum != ext4_superblock_csum(sb, es)) {
+ ext4_msg(sb, KERN_ERR, "external journal has "
+ "corrupt superblock");
+ brelse(bh);
+ goto out_bdev;
+ }
+
if (memcmp(EXT4_SB(sb)->s_es->s_journal_uuid, es->s_uuid, 16)) {
ext4_msg(sb, KERN_ERR, "journal UUID does not match");
brelse(bh);