From: Deepanshu Kartikey kartikey406@gmail.com
[ Upstream commit 1d3ad183943b38eec2acf72a0ae98e635dc8456b ]
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 [ Adjust context ] Signed-off-by: Sasha Levin sashal@kernel.org --- fs/ext4/inode.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index fe54c84a1df09..99eab1157d04f 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -5071,6 +5071,14 @@ 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); + /* 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))