| #! /bin/bash |
| # SPDX-License-Identifier: GPL-2.0 |
| # Copyright (c) 2017 Oracle, Inc. All Rights Reserved. |
| # |
| # FSQA Test No. 134 |
| # |
| # Since loff_t is a signed type, it is invalid for a filesystem to load |
| # an inode with i_size = -1ULL. Unfortunately, nobody checks this, |
| # which means that we can trivially DoS the VFS by creating such a file |
| # and appending to it. This causes an integer overflow in the routines |
| # underlying writeback, which results in the kernel locking up. |
| # |
| # So, create this malformed inode and try a dio append to make sure we |
| # catch this situation. |
| # |
| seq=`basename $0` |
| seqres=$RESULT_DIR/$seq |
| echo "QA output created by $seq" |
| |
| PIDS="" |
| tmp=/tmp/$$ |
| status=1 # failure is the default! |
| trap "_cleanup; exit \$status" 0 1 2 3 15 |
| |
| _cleanup() |
| { |
| rm -f $tmp.* |
| } |
| |
| # get standard environment, filters and checks |
| . ./common/rc |
| . ./common/filter |
| |
| # real QA test starts here |
| _supported_fs xfs |
| _require_scratch_nocheck |
| _disable_dmesg_check |
| |
| rm -f $seqres.full |
| |
| echo "Format and mount" |
| _scratch_mkfs >> $seqres.full 2>&1 |
| _scratch_mount |
| |
| testdir=$SCRATCH_MNT |
| # make sure the write offset is 512-aligned |
| touch $testdir/a |
| inum=$(stat -c "%i" $testdir/a) |
| |
| echo "Corrupt filesystem" |
| _scratch_unmount |
| |
| # 1) Set the file size to the highest multiple of 512 below -1 so |
| # that we can perform a dio write. |
| # 2) run two xfs_db commands to set core.size regardless of the special |
| # argument "--" is needed or not. |
| _scratch_xfs_db -x -c "inode ${inum}" -c 'write core.size -- -512' >> $seqres.full 2>&1 |
| _scratch_xfs_db -x -c "inode ${inum}" -c 'write core.size -512' >> $seqres.full 2>&1 |
| |
| # check core.size and _notrun if it's not set correctly |
| i_size=`_scratch_xfs_db -c "inode ${inum}" -c "print core.size" | $AWK_PROG '{print $3}'` |
| if [ $i_size -ne -512 ]; then |
| _notrun "Could not set i_size to -512 successfully, skip test." |
| fi |
| |
| echo "Remount, try to append" |
| _scratch_mount |
| dd if=/dev/zero of=$testdir/a bs=512 count=1 oflag=direct,append conv=notrunc >> $seqres.full 2>&1 || echo "Write did not succeed (ok)." |
| sync |
| |
| # success, all done |
| status=0 |
| exit |