From eea750a5623ddac7a61982eec8f1c93481857578 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Thu, 3 Apr 2014 19:50:56 +0300 Subject: virtio-net: out-of-bounds buffer write on invalid state load CVE-2013-4150 QEMU 1.5.0 out-of-bounds buffer write in virtio_net_load()@hw/net/virtio-net.c This code is in hw/net/virtio-net.c: if (n->max_queues > 1) { if (n->max_queues != qemu_get_be16(f)) { error_report("virtio-net: different max_queues "); return -1; } n->curr_queues = qemu_get_be16(f); for (i = 1; i < n->curr_queues; i++) { n->vqs[i].tx_waiting = qemu_get_be32(f); } } Number of vqs is max_queues, so if we get invalid input here, for example if max_queues = 2, curr_queues = 3, we get write beyond end of the buffer, with data that comes from wire. This might be used to corrupt qemu memory in hard to predict ways. Since we have lots of function pointers around, RCE might be possible. Signed-off-by: Michael S. Tsirkin Acked-by: Jason Wang Reviewed-by: Michael Roth Signed-off-by: Juan Quintela --- hw/net/virtio-net.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'hw/net/virtio-net.c') diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c index 33bd233a2d..0a8cb40b92 100644 --- a/hw/net/virtio-net.c +++ b/hw/net/virtio-net.c @@ -1407,6 +1407,11 @@ static int virtio_net_load(QEMUFile *f, void *opaque, int version_id) } n->curr_queues = qemu_get_be16(f); + if (n->curr_queues > n->max_queues) { + error_report("virtio-net: curr_queues %x > max_queues %x", + n->curr_queues, n->max_queues); + return -1; + } for (i = 1; i < n->curr_queues; i++) { n->vqs[i].tx_waiting = qemu_get_be32(f); } -- cgit v1.2.3 From 98f93ddd84800f207889491e0b5d851386b459cf Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Mon, 28 Apr 2014 16:08:21 +0300 Subject: virtio-net: out-of-bounds buffer write on load 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(-) (limited to 'hw/net/virtio-net.c') diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c index 0a8cb40b92..940a7cfe54 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; } -- cgit v1.2.3