From 8cdb5240ec5928b20490a2bb34cb87e9a5f40226 Mon Sep 17 00:00:00 2001
From: Theodore Ts'o <tytso@mit.edu>
Date: Sat, 16 Jun 2018 15:40:48 -0400
Subject: [PATCH] ext4: never move the system.data xattr out of the inode body
Git-commit: 8cdb5240ec5928b20490a2bb34cb87e9a5f40226
Patch-mainline: v4.18-rc4
References: bsc#1099845 cve-2018-10880
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
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Acked-by: Jan Kara <jack@suse.cz>
---
fs/ext4/xattr.c | 5 +++++
1 file changed, 5 insertions(+)
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -1434,6 +1434,11 @@ static int ext4_xattr_make_inode_space(h
last = IFIRST(header);
/* Find the entry best suited to be pushed into EA block */
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);