diff options
| author | Deepanshu Kartikey <kartikey406@gmail.com> | 2025-09-30 16:58:10 +0530 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2025-10-10 16:42:51 -0400 |
| commit | 1d3ad183943b38eec2acf72a0ae98e635dc8456b (patch) | |
| tree | 9f80b9ca7d1cb87a005f6ccff49a9ad6105e79a8 | |
| parent | 4b471b736ea1ce08113a12bd7dcdaea621b0f65f (diff) | |
ext4: detect invalid INLINE_DATA + EXTENTS flag combination
syzbot reported a BUG_ON in ext4_es_cache_extent() when opening a verity
file on a corrupted ext4 filesystem mounted without a journal.
The issue is that the filesystem has an inode with both the INLINE_DATA
and EXTENTS flags set:
EXT4-fs error (device loop0): ext4_cache_extents:545: inode #15:
comm syz.0.17: corrupted extent tree: lblk 0 < prev 66
Investigation revealed that the inode has both flags set:
DEBUG: inode 15 - flag=1, i_inline_off=164, has_inline=1, extents_flag=1
This is an invalid combination since an inode should have either:
- INLINE_DATA: data stored directly in the inode
- EXTENTS: data stored in extent-mapped blocks
Having both flags causes ext4_has_inline_data() to return true, skipping
extent tree validation in __ext4_iget(). The unvalidated out-of-order
extents then trigger a BUG_ON in ext4_es_cache_extent() due to integer
underflow when calculating hole sizes.
Fix this by detecting this invalid flag combination early in ext4_iget()
and rejecting the corrupted inode.
Cc: stable@kernel.org
Reported-and-tested-by: syzbot+038b7bf43423e132b308@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=038b7bf43423e132b308
Suggested-by: Zhang Yi <yi.zhang@huawei.com>
Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Message-ID: <20250930112810.315095-1-kartikey406@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
| -rw-r--r-- | fs/ext4/inode.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index f9e4ac87211e..e99306a8f47c 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -5319,6 +5319,14 @@ struct inode *__ext4_iget(struct super_block *sb, unsigned long ino, } ei->i_flags = le32_to_cpu(raw_inode->i_flags); ext4_set_inode_flags(inode, true); + /* Detect invalid flag combination - can't have both inline data and extents */ + if (ext4_test_inode_flag(inode, EXT4_INODE_INLINE_DATA) && + ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) { + ext4_error_inode(inode, function, line, 0, + "inode has both inline data and extents flags"); + ret = -EFSCORRUPTED; + goto bad_inode; + } inode->i_blocks = ext4_inode_blocks(raw_inode, ei); ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl_lo); if (ext4_has_feature_64bit(sb)) |