2 # SPDX-License-Identifier: GPL-2.0
3 # Copyright (c) 2017 Oracle, Inc. All Rights Reserved.
7 # Since loff_t is a signed type, it is invalid for a filesystem to load
8 # an inode with i_size = -1ULL. Unfortunately, nobody checks this,
9 # which means that we can trivially DoS the VFS by creating such a file
10 # and appending to it. This causes an integer overflow in the routines
11 # underlying writeback, which results in the kernel locking up.
13 # So, create this malformed inode and try a buffered append to make
14 # sure we catch this situation.
17 _begin_fstest dangerous_fuzzers
21 # Import common functions.
24 # real QA test starts here
26 _require_scratch_nocheck
29 echo "Format and mount"
30 _scratch_mkfs >> $seqres.full 2>&1
35 inum=$(stat -c "%i" $testdir/a)
37 echo "Corrupt filesystem"
40 # run two xfs_db commands to set core.size regardless of the special argument "--"
42 _scratch_xfs_db -x -c "inode ${inum}" -c 'write core.size -- -1' >> $seqres.full 2>&1
43 _scratch_xfs_db -x -c "inode ${inum}" -c 'write core.size -1' >> $seqres.full 2>&1
45 # check core.size and _notrun if it's not set correctly
46 i_size=`_scratch_xfs_db -c "inode ${inum}" -c "print core.size" | $AWK_PROG '{print $3}'`
47 if [ $i_size -ne -1 ]; then
48 _notrun "Could not set i_size to -1 successfully, skip test."
51 echo "Remount, try to append"
53 dd if=/dev/zero of=$testdir/a bs=512 count=1 oflag=append conv=notrunc >> $seqres.full 2>&1 || echo "Write did not succeed (ok)."