vpc: Validate block size (CVE-2014-0142)

This fixes some cases of division by zero crashes.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

block/vpc.c

@@ -245,6 +245,11 @@ static int vpc_open(BlockDriverState *bs, QDict *options, int flags,
         }
 
         s->block_size = be32_to_cpu(dyndisk_header->block_size);
+        if (!is_power_of_2(s->block_size) || s->block_size < BDRV_SECTOR_SIZE) {
+            error_setg(errp, "Invalid block size %" PRIu32, s->block_size);
+            ret = -EINVAL;
+            goto fail;
+        }
         s->bitmap_size = ((s->block_size / (8 * 512)) + 511) & ~511;
 
         s->max_table_entries = be32_to_cpu(dyndisk_header->max_table_entries);

tests/qemu-iotests/088

@@ -0,0 +1,64 @@
+#!/bin/bash
+#
+# vpc (VHD) format input validation tests
+#
+# Copyright (C) 2014 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()
+{
+    rm -f $TEST_IMG.snap
+    _cleanup_test_img
+}
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+# get standard environment, filters and checks
+. ./common.rc
+. ./common.filter
+
+_supported_fmt vpc
+_supported_proto generic
+_supported_os Linux
+
+offset_block_size=$((512 + 32))
+
+echo
+echo "== Invalid block size =="
+_make_test_img 64M
+poke_file "$TEST_IMG" "$offset_block_size" "\x00\x00\x00\x00"
+{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
+{ $QEMU_IO -c "write 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
+poke_file "$TEST_IMG" "$offset_block_size" "\x00\x00\x00\x80"
+{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
+{ $QEMU_IO -c "write 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
+poke_file "$TEST_IMG" "$offset_block_size" "\x12\x34\x56\x78"
+{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
+{ $QEMU_IO -c "write 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
+
+# success, all done
+echo "*** done"
+rm -f $seq.full
+status=0

tests/qemu-iotests/088.out

@@ -0,0 +1,17 @@
+QA output created by 088
+
+== Invalid block size ==
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 
+qemu-io: can't open device TEST_DIR/t.vpc: Invalid block size 0
+no file open, try 'help open'
+qemu-io: can't open device TEST_DIR/t.vpc: Invalid block size 0
+no file open, try 'help open'
+qemu-io: can't open device TEST_DIR/t.vpc: Invalid block size 128
+no file open, try 'help open'
+qemu-io: can't open device TEST_DIR/t.vpc: Invalid block size 128
+no file open, try 'help open'
+qemu-io: can't open device TEST_DIR/t.vpc: Invalid block size 305419896
+no file open, try 'help open'
+qemu-io: can't open device TEST_DIR/t.vpc: Invalid block size 305419896
+no file open, try 'help open'
+*** done

tests/qemu-iotests/group

@@ -91,3 +91,4 @@
 085 rw auto
 086 rw auto quick
 087 rw auto
+088 rw auto