4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Theodore Ts'o <tytso@xxxxxxx> 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 Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> Cc: stable@xxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/ext4/inline.c | 1 + 1 file changed, 1 insertion(+) --- a/fs/ext4/inline.c +++ b/fs/ext4/inline.c @@ -434,6 +434,7 @@ 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) ||
