From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56190) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WVlEY-0003rH-Ed for qemu-devel@nongnu.org; Thu, 03 Apr 2014 13:15:28 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WVlES-00066d-93 for qemu-devel@nongnu.org; Thu, 03 Apr 2014 13:15:22 -0400 Date: Thu, 3 Apr 2014 19:50:43 +0300 From: "Michael S. Tsirkin" Message-ID: <1396543778-22307-6-git-send-email-mst@redhat.com> References: <1396543778-22307-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1396543778-22307-1-git-send-email-mst@redhat.com> Subject: [Qemu-devel] [PATCH v5 05/24] 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: Peter Maydell , qemu-stable@nongnu.org, dgilbert@redhat.com, Anthony Liguori , mdroth@linux.vnet.ibm.com 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 --- hw/net/virtio-net.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c index 439477b..c247529 100644 --- a/hw/net/virtio-net.c +++ b/hw/net/virtio-net.c @@ -1362,10 +1362,16 @@ 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 { + int 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. + */ + for (i = 0; i < 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; } -- MST