From 953a3b8344e504a7333ba9bb6df840d6d94ff872 Mon Sep 17 00:00:00 2001
From: Michael S. Tsirkin <mst@redhat.com>
Date: Wed, 14 May 2014 08:31:47 +0200
Subject: [PATCH 10/31] virtio-net: out-of-bounds buffer write on invalid state load

RH-Author: Michael S. Tsirkin <mst@redhat.com>
Message-id: <1400056285-6688-3-git-send-email-mst@redhat.com>
Patchwork-id: 58857
O-Subject: [PATCH qemu-kvm RHEL7.1] virtio-net: out-of-bounds buffer write on invalid state load
Bugzilla: 1095690
RH-Acked-by: Dr. David Alan Gilbert (git) <dgilbert@redhat.com>
RH-Acked-by: Xiao Wang <jasowang@redhat.com>
RH-Acked-by: Juan Quintela <quintela@redhat.com>

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 <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
(cherry picked from commit eea750a5623ddac7a61982eec8f1c93481857578)

Tested: lightly on developer's box
Brew build: http://brewweb.devel.redhat.com/brew/taskinfo?taskID=7452039
Bugzilla: 1095690
---
 hw/net/virtio-net.c | 5 +++++
 1 file changed, 5 insertions(+)

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 hw/net/virtio-net.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 2d559e0..007cc2a 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -1327,6 +1327,11 @@ 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);
         }
-- 
1.7.1