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From: Theodore Ts'o <tytso@mit.edu>
Date: Fri, 15 Jun 2018 12:28:16 -0400
Subject: ext4: clear i_data in ext4_inode_info when removing inline data
Origin: https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git/commit?id=cd75e020ee28aa21985c6d8ebafc7457b4c51531
Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2018-10881
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
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
fs/ext4/inline.c | 1 +
1 file changed, 1 insertion(+)
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -437,6 +437,7 @@ static int ext4_destroy_inline_data_nolo
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) ||
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