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ext4: validate ea_ino and size in check_xattrs 

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.

Cc: stable@kernel.org
Suggested-by: Theodore Ts'o <tytso@mit.edu>
Reported-by: syzbot+4c9d23743a2409b80293@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?extid=4c9d23743a2409b80293
Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Message-ID: <20250923133245.1091761-1-kartikey406@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Deepanshu Kartikey 2025-09-23 19:02:45 +05:30 committed by Theodore Ts'o
parent 57295e8354
commit 44d2a72f4d
1 changed files with 4 additions and 0 deletions
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4
fs/ext4/xattr.c
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@ -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;