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qemu/tests/qemu-iotests/080
Kevin Wolf b106ad9185 qcow2: Don't rely on free_cluster_index in alloc_refcount_block() (CVE-2014-0147) 
free_cluster_index is only correct if update_refcount() was called from
an allocation function, and even there it's brittle because it's used to
protect unfinished allocations which still have a refcount of 0 - if it
moves in the wrong place, the unfinished allocation can be corrupted.

So not using it any more seems to be a good idea. Instead, use the
first requested cluster to do the calculations. Return -EAGAIN if
unfinished allocations could become invalid and let the caller restart
its search for some free clusters.

The context of creating a snapsnot is one situation where
update_refcount() is called outside of a cluster allocation. For this
case, the change fixes a buffer overflow if a cluster is referenced in
an L2 table that cannot be represented by an existing refcount block.
(new_table[refcount_table_index] was out of bounds)

[Bump the qemu-iotests 026 refblock_alloc.write leak count from 10 to
11.
--Stefan]

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2014-04-01 15:21:03 +02:00

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#!/bin/bash
#
# qcow2 format input validation tests
#
# Copyright (C) 2013 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=kwolf@redhat.com
seq=`basename $0`
echo "QA output created by $seq"
here=`pwd`
tmp=/tmp/$$
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
_supported_fmt qcow2
_supported_proto generic
_supported_os Linux
header_size=104
offset_backing_file_offset=8
offset_backing_file_size=16
offset_l1_size=36
offset_l1_table_offset=40
offset_refcount_table_offset=48
offset_refcount_table_clusters=56
offset_nb_snapshots=60
offset_snapshots_offset=64
offset_header_size=100
offset_ext_magic=$header_size
offset_ext_size=$((header_size + 4))
offset_l2_table_0=$((0x40000))
echo
echo "== Huge header size =="
_make_test_img 64M
poke_file "$TEST_IMG" "$offset_header_size" "\xff\xff\xff\xff"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
poke_file "$TEST_IMG" "$offset_header_size" "\x7f\xff\xff\xff"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
echo
echo "== Huge unknown header extension =="
_make_test_img 64M
poke_file "$TEST_IMG" "$offset_backing_file_offset" "\xff\xff\xff\xff\xff\xff\xff\xff"
poke_file "$TEST_IMG" "$offset_ext_magic" "\x12\x34\x56\x78"
poke_file "$TEST_IMG" "$offset_ext_size" "\x7f\xff\xff\xff"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
poke_file "$TEST_IMG" "$offset_backing_file_offset" "\x00\x00\x00\x00\x00\x00\x00\x00"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
echo
echo "== Huge refcount table size =="
_make_test_img 64M
poke_file "$TEST_IMG" "$offset_refcount_table_clusters" "\xff\xff\xff\xff"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
poke_file "$TEST_IMG" "$offset_refcount_table_clusters" "\x00\x02\x00\x01"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
echo
echo "== Misaligned refcount table =="
_make_test_img 64M
poke_file "$TEST_IMG" "$offset_refcount_table_offset" "\x12\x34\x56\x78\x90\xab\xcd\xef"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
echo
echo "== Huge refcount offset =="
_make_test_img 64M
poke_file "$TEST_IMG" "$offset_refcount_table_offset" "\xff\xff\xff\xff\xff\xff\x00\x00"
poke_file "$TEST_IMG" "$offset_refcount_table_clusters" "\x00\x00\x00\x7f"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
echo
echo "== Invalid snapshot table =="
_make_test_img 64M
poke_file "$TEST_IMG" "$offset_nb_snapshots" "\xff\xff\xff\xff"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
poke_file "$TEST_IMG" "$offset_nb_snapshots" "\x7f\xff\xff\xff"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
poke_file "$TEST_IMG" "$offset_snapshots_offset" "\xff\xff\xff\xff\xff\xff\x00\x00"
poke_file "$TEST_IMG" "$offset_nb_snapshots" "\x00\x00\xff\xff"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
poke_file "$TEST_IMG" "$offset_snapshots_offset" "\x12\x34\x56\x78\x90\xab\xcd\xef"
poke_file "$TEST_IMG" "$offset_nb_snapshots" "\x00\x00\x00\x00"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
echo
echo "== Hitting snapshot table size limit =="
_make_test_img 64M
# Put the refcount table in a more or less safe place (16 MB)
poke_file "$TEST_IMG" "$offset_snapshots_offset" "\x00\x00\x00\x00\x01\x00\x00\x00"
poke_file "$TEST_IMG" "$offset_nb_snapshots" "\x00\x01\x00\x00"
{ $QEMU_IMG snapshot -c test $TEST_IMG; } 2>&1 | _filter_testdir
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
echo
echo "== Invalid L1 table =="
_make_test_img 64M
poke_file "$TEST_IMG" "$offset_l1_size" "\xff\xff\xff\xff"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
poke_file "$TEST_IMG" "$offset_l1_size" "\x7f\xff\xff\xff"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
poke_file "$TEST_IMG" "$offset_l1_table_offset" "\x7f\xff\xff\xff\xff\xff\x00\x00"
poke_file "$TEST_IMG" "$offset_l1_size" "\x00\x00\xff\xff"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
poke_file "$TEST_IMG" "$offset_l1_table_offset" "\x12\x34\x56\x78\x90\xab\xcd\xef"
poke_file "$TEST_IMG" "$offset_l1_size" "\x00\x00\x00\x01"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
echo
echo "== Invalid backing file size =="
_make_test_img 64M
poke_file "$TEST_IMG" "$offset_backing_file_offset" "\x00\x00\x00\x00\x00\x00\x10\x00"
poke_file "$TEST_IMG" "$offset_backing_file_size" "\xff\xff\xff\xff"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
echo
echo "== Invalid L2 entry (huge physical offset) =="
_make_test_img 64M
{ $QEMU_IO -c "write 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
poke_file "$TEST_IMG" "$offset_l2_table_0" "\xbf\xff\xff\xff\xff\xff\x00\x00"
{ $QEMU_IMG snapshot -c test $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
poke_file "$TEST_IMG" "$offset_l2_table_0" "\x80\x00\x00\xff\xff\xff\x00\x00"
{ $QEMU_IMG snapshot -c test $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
# success, all done
echo "*** done"
rm -f $seq.full
status=0
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