xemu/tests/qemu-iotests/138
Vladimir Sementsov-Ogievskiy a5fff8d4b4 qcow2-refcount: avoid eating RAM
qcow2_inc_refcounts_imrt() (through realloc_refcount_array()) can eat
an unpredictable amount of memory on corrupted table entries, which are
referencing regions far beyond the end of file.

Prevent this, by skipping such regions from further processing.

Interesting that iotest 138 checks exactly the behavior which we fix
here. So, change the test appropriately.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190227131433.197063-3-vsementsov@virtuozzo.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
2019-05-07 17:14:21 +02:00

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#!/usr/bin/env bash
#
# General test case for qcow2's image check
#
# Copyright (C) 2015 Red Hat, Inc.
#
# 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; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will 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, see <http://www.gnu.org/licenses/>.
#
# creator
owner=mreitz@redhat.com
seq="$(basename $0)"
echo "QA output created by $seq"
status=1 # failure is the default!
_cleanup()
{
_cleanup_test_img
}
trap "_cleanup; exit \$status" 0 1 2 3 15
# get standard environment, filters and checks
. ./common.rc
. ./common.filter
# This tests qocw2-specific low-level functionality
_supported_fmt qcow2
_supported_proto file
_supported_os Linux
echo
echo '=== Check on an image with a multiple of 2^32 clusters ==='
echo
IMGOPTS=$(_optstr_add "$IMGOPTS" "cluster_size=512") \
_make_test_img 512
# Allocate L2 table
$QEMU_IO -c 'write 0 512' "$TEST_IMG" | _filter_qemu_io
# Put the data cluster at a multiple of 2 TB, resulting in the image apparently
# having a multiple of 2^32 clusters
# (To be more specific: It is at 32 PB)
poke_file "$TEST_IMG" $((2048 + 8)) "\x00\x80\x00\x00\x00\x00\x00\x00"
# An offset of 32 PB results in qemu-img check having to allocate an in-memory
# refcount table of 128 TB (16 bit refcounts, 512 byte clusters), if qemu-img
# don't check that referenced data cluster is far beyond the end of file.
# But starting from 4.0, qemu-img does this check, and instead of "Cannot
# allocate memory", we have an error showing that l2 entry is invalid.
_check_test_img
# success, all done
echo "*** done"
rm -f $seq.full
status=0