From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54892) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wjpu9-0002CO-Ic for qemu-devel@nongnu.org; Mon, 12 May 2014 09:04:35 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Wjpu3-0003Qj-9l for qemu-devel@nongnu.org; Mon, 12 May 2014 09:04:29 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42357) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wjpu3-0003Qa-0W for qemu-devel@nongnu.org; Mon, 12 May 2014 09:04:23 -0400 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s4CD4MbM023597 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Mon, 12 May 2014 09:04:22 -0400 From: Kevin Wolf Date: Mon, 12 May 2014 15:04:09 +0200 Message-Id: <1399899851-5641-4-git-send-email-kwolf@redhat.com> In-Reply-To: <1399899851-5641-1-git-send-email-kwolf@redhat.com> References: <1399899851-5641-1-git-send-email-kwolf@redhat.com> Subject: [Qemu-devel] [PATCH 3/5] qcow1: Validate L2 table size (CVE-2014-0222) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: kwolf@redhat.com, stefanha@redhat.com, ppandit@redhat.com Too large L2 table sizes cause unbounded allocations. Images actually created by qemu-img only have 512 byte or 4k L2 tables. To keep things consistent with cluster sizes, allow ranges between 512 bytes and 64k (in fact, down to 1 entry = 8 bytes is technically working, but L2 table sizes smaller than a cluster don't make a lot of sense). This also means that the number of bytes on the virtual disk that are described by the same L2 table is limited to at most 8k * 64k or 2^29, preventively avoiding any integer overflows. Signed-off-by: Kevin Wolf --- block/qcow.c | 8 ++++++++ tests/qemu-iotests/092 | 10 ++++++++++ tests/qemu-iotests/092.out | 7 +++++++ 3 files changed, 25 insertions(+) diff --git a/block/qcow.c b/block/qcow.c index e60df23..e8038e5 100644 --- a/block/qcow.c +++ b/block/qcow.c @@ -139,6 +139,14 @@ static int qcow_open(BlockDriverState *bs, QDict *options, int flags, goto fail; } + /* l2_bits specifies number of entries; storing a uint64_t in each entry, + * so bytes = num_entries << 3. */ + if (header.l2_bits < 9 - 3 || header.l2_bits > 16 - 3) { + error_setg(errp, "L2 table size must be between 512 and 64k"); + ret = -EINVAL; + goto fail; + } + if (header.crypt_method > QCOW_CRYPT_AES) { error_setg(errp, "invalid encryption method in qcow header"); ret = -EINVAL; diff --git a/tests/qemu-iotests/092 b/tests/qemu-iotests/092 index b0f04e3..2196cce 100755 --- a/tests/qemu-iotests/092 +++ b/tests/qemu-iotests/092 @@ -54,6 +54,16 @@ poke_file "$TEST_IMG" "$offset_cluster_bits" "\xff" poke_file "$TEST_IMG" "$offset_cluster_bits" "\x1f" { $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir +echo +echo "== Invalid L2 table size ==" +_make_test_img 64M +poke_file "$TEST_IMG" "$offset_l2_bits" "\xff" +{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir + +# 1 << 0x1b = 2^31 / L2_CACHE_SIZE +poke_file "$TEST_IMG" "$offset_l2_bits" "\x1b" +{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir + # success, all done echo "*** done" rm -f $seq.full diff --git a/tests/qemu-iotests/092.out b/tests/qemu-iotests/092.out index 9e7367a..45a7ac8 100644 --- a/tests/qemu-iotests/092.out +++ b/tests/qemu-iotests/092.out @@ -6,4 +6,11 @@ qemu-io: can't open device TEST_DIR/t.qcow: Cluster size must be between 512 and no file open, try 'help open' qemu-io: can't open device TEST_DIR/t.qcow: Cluster size must be between 512 and 64k no file open, try 'help open' + +== Invalid L2 table size == +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 +qemu-io: can't open device TEST_DIR/t.qcow: L2 table size must be between 512 and 64k +no file open, try 'help open' +qemu-io: can't open device TEST_DIR/t.qcow: L2 table size must be between 512 and 64k +no file open, try 'help open' *** done -- 1.8.3.1