ext4: CVE-2018-10881

ext4: clear i_data in ext4_inode_info when removing inline data

Reference:
https://nvd.nist.gov/vuln/detail/CVE-2018-10881
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-4.14.y&id=deb465ec750b80776cc4ac5b92b72c0a71fd4f0b

Change-Id: I45dcf13bbc72e3ae398117481cc7899d4f58c960
Signed-off-by: Andreas Wellving <andreas.wellving@enea.com>

1 files changed, 55 insertions, 0 deletions

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..9cd1f86
--- /dev/null
+++ b/patches/cve/CVE-2018-10881-ext4-clear-i_data-in-ext4_inode_info-when-removing-i.patch
@@ -0,0 +1,55 @@
+From deb465ec750b80776cc4ac5b92b72c0a71fd4f0b 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
+
+commit 6e8ab72a812396996035a37e5ca4b3b99b5d214b upstream.
+
+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.
+
+https://bugzilla.kernel.org/show_bug.cgi?id=200015
+
+CVE: CVE-2018-10881
+Upstream-Status: Backport [https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-4.14.y&id=deb465ec750b80776cc4ac5b92b72c0a71fd4f0b]
+
+Signed-off-by: Theodore Ts'o <tytso@mit.edu>
+Cc: stable@kernel.org
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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 8f5dc243effd..afdef31ff728 100644
+--- a/fs/ext4/inline.c
++++ b/fs/ext4/inline.c
+@@ -443,6 +443,7 @@ 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) ||
+-- 
+2.20.1
+