From: Theodore Ts'o 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 --- 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) ||