From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36656) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XF81D-0005Ip-Kk for qemu-devel@nongnu.org; Wed, 06 Aug 2014 16:41:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XF814-0003yI-DX for qemu-devel@nongnu.org; Wed, 06 Aug 2014 16:41:07 -0400 Received: from e31.co.us.ibm.com ([32.97.110.149]:34904) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XF814-0003y5-5Z for qemu-devel@nongnu.org; Wed, 06 Aug 2014 16:40:58 -0400 Received: from /spool/local by e31.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 6 Aug 2014 14:40:57 -0600 From: Michael Roth Date: Wed, 6 Aug 2014 15:38:18 -0500 Message-Id: <1407357598-21541-9-git-send-email-mdroth@linux.vnet.ibm.com> In-Reply-To: <1407357598-21541-1-git-send-email-mdroth@linux.vnet.ibm.com> References: <1407357598-21541-1-git-send-email-mdroth@linux.vnet.ibm.com> Subject: [Qemu-devel] [PATCH 008/108] 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: qemu-stable@nongnu.org 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 (cherry picked from commit 98f93ddd84800f207889491e0b5d851386b459cf) Signed-off-by: Michael Roth --- 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; } -- 1.9.1