blob: de7b84ffd7602202a38b13593051e495e019c1fa [file] [log] [blame]
#! /bin/bash
# FSQA Test No. 005
#
# 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 buffered append to make
# sure we catch this situation.
#
#-----------------------------------------------------------------------
# Copyright (c) 2017 Oracle, Inc. All Rights Reserved.
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it would be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write the Free Software Foundation,
# Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
#-----------------------------------------------------------------------
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 $tmp.*
}
# get standard environment, filters and checks
. ./common/rc
. ./common/filter
# real QA test starts here
_supported_os Linux
_supported_fs ext2 ext3 ext4
_require_scratch_nocheck
_disable_dmesg_check
_require_command "$DEBUGFS_PROG"
rm -f $seqres.full
echo "Format and mount"
_scratch_mkfs >> $seqres.full 2>&1
_scratch_mount
testdir=$SCRATCH_MNT
echo m > $testdir/a
echo "Corrupt filesystem"
_scratch_unmount
$DEBUGFS_PROG -w -R "sif /a size -1" $SCRATCH_DEV >> $seqres.full 2>&1
# check whether debugfs succeeds to set i_size to -1 or not
$DEBUGFS_PROG -R "stat /a" $SCRATCH_DEV 2>&1 | grep -q "Size: 18446744073709551615" || \
_notrun "Could not set i_size to -1 successfully, skip test."
echo "Remount, try to append"
_scratch_mount
dd if=/dev/zero of=$testdir/a bs=512 count=1 oflag=append conv=notrunc >> $seqres.full 2>&1 || echo "Write did not succeed (ok)."
sync
# success, all done
status=0
exit