From: Theodore Ts'o tytso@mit.edu

commit 8cdb5240ec5928b20490a2bb34cb87e9a5f40226 upstream.

When expanding the extra isize space, we must never move the system.data xattr out of the inode body. For performance reasons, it doesn't make any sense, and the inline data implementation assumes that system.data xattr is never in the external xattr block.

This addresses CVE-2018-10880

https://bugzilla.kernel.org/show_bug.cgi?id=200005

Backport Note: - dfa2064b22("ext4: factor out loop for freeing inode xattr space") factored out the loop from inside ext4_expand_extra_isize_ea to a separate function named ext4_xattr_make_inode_space. As the above commit is not present in 4.4.y, make the change inside ext4_expand_extra_isize_ea.

Signed-off-by: Theodore Ts'o tytso@mit.edu Cc: stable@kernel.org Signed-off-by: Zubin Mithra zsm@chromium.org --- fs/ext4/xattr.c | 5 +++++ 1 file changed, 5 insertions(+)

diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c index 9fb2a751fce4..b51bb73b06a6 100644 --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -1386,6 +1386,11 @@ retry: /* Find the entry best suited to be pushed into EA block */ entry = NULL; for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) { + /* never move system.data out of the inode */ + if ((last->e_name_len == 4) && + (last->e_name_index == EXT4_XATTR_INDEX_SYSTEM) && + !memcmp(last->e_name, "data", 4)) + continue; total_size = EXT4_XATTR_SIZE(le32_to_cpu(last->e_value_size)) + EXT4_XATTR_LEN(last->e_name_len);