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authorTheodore Ts'o <tytso@mit.edu>2022-05-17 20:27:55 +0300
committerTheodore Ts'o <tytso@mit.edu>2022-05-24 22:33:58 +0300
commitc878bea3c9d724ddfa05a813f30de3d25a0ba83f (patch)
treee5f9d22f52390a38738844e24d49b6f0e617ad3a /fs/ext4
parentef09ed5d37b84d18562b30cf7253e57062d0db05 (diff)
downloadlinux-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.c5
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)