ext4: CVE-2018-10881

ext4: clear i_data in ext4_inode_info when removing inline data

References:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=6e8ab72a812396996035a37e5ca4b3b99b5d214b

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

Change-Id: I1070aa3fee30f445dfad0b86fc12787f7f50235d

2 files changed, 51 insertions, 0 deletions

diff --git a/patches/cve/4.9.x.scc b/patches/cve/4.9.x.scc
index e5bf4ac..55c4591 100644
--- a/patches/cve/4.9.x.scc
+++ b/patches/cve/4.9.x.scc
@@ -31,4 +31,5 @@ patch CVE-2018-10876-ext4-only-look-at-the-bg_flags-field-if-it-is-valid.patch
 patch CVE-2018-10877-ext4-verify-the-depth-of-extent-tree-in-ext4_find_ex.patch
 patch CVE-2018-10878-ext4-always-check-block-group-bounds-in-ext4_init_bl.patch
 patch CVE-2018-10879-ext4-make-sure-bitmaps-and-the-inode-table-don-t-ove.patch
+patch CVE-2018-10881-ext4-clear-i_data-in-ext4_inode_info-when-removing-i.patch
 
diff --git a/patches/cve/CVE-2018-10881-ext4-clear-i_data-in-ext4_inode_info-when-removing-i.patch b/patches/cve/CVE-2018-10881-ext4-clear-i_data-in-ext4_inode_info-when-removing-i.patch
new file mode 100644
index 0000000..1abf375
--- /dev/null
+++ b/patches/cve/CVE-2018-10881-ext4-clear-i_data-in-ext4_inode_info-when-removing-i.patch
@@ -0,0 +1,50 @@
+From 6e8ab72a812396996035a37e5ca4b3b99b5d214b Mon Sep 17 00:00:00 2001
+From: Theodore Ts'o <tytso@mit.edu>
+Date: Fri, 15 Jun 2018 12:28:16 -0400
+Subject: [PATCH] ext4: clear i_data in ext4_inode_info when removing inline
+ data
+
+When converting from an inode from storing the data in-line to a data
+block, ext4_destroy_inline_data_nolock() was only clearing the on-disk
+copy of the i_blocks[] array.  It was not clearing copy of the
+i_blocks[] in ext4_inode_info, in i_data[], which is the copy actually
+used by ext4_map_blocks().
+
+This didn't matter much if we are using extents, since the extents
+header would be invalid and thus the extents could would re-initialize
+the extents tree.  But if we are using indirect blocks, the previous
+contents of the i_blocks array will be treated as block numbers, with
+potentially catastrophic results to the file system integrity and/or
+user data.
+
+This gets worse if the file system is using a 1k block size and
+s_first_data is zero, but even without this, the file system can get
+quite badly corrupted.
+
+This addresses CVE-2018-10881.
+Upstream-Status: Backport  
+
+https://bugzilla.kernel.org/show_bug.cgi?id=200015
+
+Signed-off-by: Theodore Ts'o <tytso@mit.edu>
+Cc: stable@kernel.org
+Signed-off-by: Andreas Wellving <andreas.wellving@enea.com>
+---
+ fs/ext4/inline.c | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
+index 44b4fcd..d79115d 100644
+--- a/fs/ext4/inline.c
++++ b/fs/ext4/inline.c
+@@ -437,6 +437,7 @@ static int ext4_destroy_inline_data_nolock(handle_t *handle,
+ 
+        memset((void *)ext4_raw_inode(&is.iloc)->i_block,
+                0, EXT4_MIN_INLINE_DATA_SIZE);
++       memset(ei->i_data, 0, EXT4_MIN_INLINE_DATA_SIZE);
+ 
+        if (ext4_has_feature_extents(inode->i_sb)) {
+                if (S_ISDIR(inode->i_mode) ||
+-- 
+
+