linux/debian/patches/bugfix/all/ext4-never-move-the-system....

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From: Theodore Ts'o <tytso@mit.edu>
Date: Sat, 16 Jun 2018 15:40:48 -0400
Subject: ext4: never move the system.data xattr out of the inode body
Origin: https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git/commit?id=896003d9fd652666080a06411d4238ee6eb4fb76
Bug-Debian-Security: https://security-tracker.debian.org/tracker/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>
---
fs/ext4/xattr.c | 5 +++++
1 file changed, 5 insertions(+)
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -2657,6 +2657,11 @@ 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_LEN(last->e_name_len);
if (!last->e_value_inum)
total_size += EXT4_XATTR_SIZE(