ext4: CVE-2018-10880

ext4: never move the system.data xattr out of the inode body

References:
https://nvd.nist.gov/vuln/detail/CVE-2018-10880
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-4.9.y&id=3a282476161c54df1a2ef1ba664c8a3514ef49f4

Change-Id: I5a9cc26679b67e63059e9a4a3728f3ee1e68d57e
Signed-off-by: Andreas Wellving <andreas.wellving@enea.com>

2 files changed, 51 insertions, 0 deletions

diff --git a/patches/cve/4.9.x.scc b/patches/cve/4.9.x.scc
index 9f87873..935280b 100644
--- a/patches/cve/4.9.x.scc
+++ b/patches/cve/4.9.x.scc
@@ -55,6 +55,9 @@ patch CVE-2018-14617-hfsplus-fix-NULL-dereference-in-hfsplus_lookup.patch
 #CVEs fixed in 4.9.128:
 patch CVE-2018-13099-f2fs-fix-to-do-sanity-check-with-reserved-blkaddr-of.patch
 
+#CVEs fixed in 4.9.131:
+patch CVE-2018-10880-ext4-never-move-the-system.data-xattr-out-of-the-ino.patch
+
 #CVEs fixed in 4.9.138:
 patch CVE-2018-16871-nfsd-COPY-and-CLONE-operations-require-the-saved-fil.patch
 
diff --git a/patches/cve/CVE-2018-10880-ext4-never-move-the-system.data-xattr-out-of-the-ino.patch b/patches/cve/CVE-2018-10880-ext4-never-move-the-system.data-xattr-out-of-the-ino.patch
new file mode 100644
index 0000000..d6220ca
--- /dev/null
+++ b/patches/cve/CVE-2018-10880-ext4-never-move-the-system.data-xattr-out-of-the-ino.patch
@@ -0,0 +1,48 @@
+From 3a282476161c54df1a2ef1ba664c8a3514ef49f4 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
+
+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
+
+CVE: CVE-2018-10880
+Upstream-Status: Backport [https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-4.9.y&id=3a282476161c54df1a2ef1ba664c8a3514ef49f4]
+
+Signed-off-by: Theodore Ts'o <tytso@mit.edu>
+Cc: stable@kernel.org
+[groeck: Context changes]
+Signed-off-by: Guenter Roeck <linux@roeck-us.net>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+Signed-off-by: Andreas Wellving <andreas.wellving@enea.com>
+---
+ fs/ext4/xattr.c | 5 +++++
+ 1 file changed, 5 insertions(+)
+
+diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
+index fdcbe0f2814f..c19c96840480 100644
+--- a/fs/ext4/xattr.c
++++ b/fs/ext4/xattr.c
+@@ -1426,6 +1426,11 @@ static int ext4_xattr_make_inode_space(handle_t *handle, struct inode *inode,
+                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);
+-- 
+2.20.1
+