During xattr block validation, check_xattrs() processes xattr entries without validating that entries claiming to use EA inodes have non-zero sizes. Corrupted filesystems may contain xattr entries where e_value_size is zero but e_value_inum is non-zero, indicating invalid xattr data. Add validation in check_xattrs() to detect this corruption pattern early and return -EFSCORRUPTED, preventing invalid xattr entries from causing issues throughout the ext4 codebase. Suggested-by: Theodore Ts'o Reported-by: syzbot+4c9d23743a2409b80293@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?extid=4c9d23743a2409b80293 Signed-off-by: Deepanshu Kartikey --- --- Changes in v2: - Moved validation from ext4_xattr_move_to_block() to check_xattrs() as suggested by Theodore Ts'o - This provides broader coverage and may address other similar syzbot reports fs/ext4/xattr.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c index 5a6fe1513fd2..d621e77c8c4d 100644 --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -251,6 +251,10 @@ check_xattrs(struct inode *inode, struct buffer_head *bh, err_str = "invalid ea_ino"; goto errout; } + if (ea_ino && !size) { + err_str = "invalid size in ea xattr"; + goto errout; + } if (size > EXT4_XATTR_SIZE_MAX) { err_str = "e_value size too large"; goto errout; -- 2.43.0