From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56789) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WhPXv-0007u0-L7 for qemu-devel@nongnu.org; Mon, 05 May 2014 16:31:37 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WhPXp-00011z-CQ for qemu-devel@nongnu.org; Mon, 05 May 2014 16:31:31 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33781) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WhPXp-00011h-4i for qemu-devel@nongnu.org; Mon, 05 May 2014 16:31:25 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s45KVOOA013408 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Mon, 5 May 2014 16:31:24 -0400 From: Juan Quintela Date: Mon, 5 May 2014 22:30:22 +0200 Message-Id: <1399321834-31310-25-git-send-email-quintela@redhat.com> In-Reply-To: <1399321834-31310-1-git-send-email-quintela@redhat.com> References: <1399321834-31310-1-git-send-email-quintela@redhat.com> Subject: [Qemu-devel] [PATCH 24/36] virtio-net: out-of-bounds buffer write on load List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: "Michael S. Tsirkin" From: "Michael S. Tsirkin" CVE-2013-4149 QEMU 1.3.0 out-of-bounds buffer write in virtio_net_load()@hw/net/virtio-net.c > } else if (n->mac_table.in_use) { > uint8_t *buf = g_malloc0(n->mac_table.in_use); We are allocating buffer of size n->mac_table.in_use > qemu_get_buffer(f, buf, n->mac_table.in_use * ETH_ALEN); and read to the n->mac_table.in_use size buffer n->mac_table.in_use * ETH_ALEN bytes, corrupting memory. If adversary controls state then memory written there is controlled by adversary. Reviewed-by: Michael Roth Signed-off-by: Michael S. Tsirkin Signed-off-by: Juan Quintela --- hw/net/virtio-net.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c index 0a8cb40..940a7cf 100644 --- a/hw/net/virtio-net.c +++ b/hw/net/virtio-net.c @@ -1362,10 +1362,17 @@ static int virtio_net_load(QEMUFile *f, void *opaque, int version_id) if (n->mac_table.in_use <= MAC_TABLE_ENTRIES) { qemu_get_buffer(f, n->mac_table.macs, n->mac_table.in_use * ETH_ALEN); - } else if (n->mac_table.in_use) { - uint8_t *buf = g_malloc0(n->mac_table.in_use); - qemu_get_buffer(f, buf, n->mac_table.in_use * ETH_ALEN); - g_free(buf); + } else { + int64_t i; + + /* Overflow detected - can happen if source has a larger MAC table. + * We simply set overflow flag so there's no need to maintain the + * table of addresses, discard them all. + * Note: 64 bit math to avoid integer overflow. + */ + for (i = 0; i < (int64_t)n->mac_table.in_use * ETH_ALEN; ++i) { + qemu_get_byte(f); + } n->mac_table.multi_overflow = n->mac_table.uni_overflow = 1; n->mac_table.in_use = 0; } -- 1.9.0