From 798f06c3737233a836584a72565f8076907365d9 Mon Sep 17 00:00:00 2001
From: Michael S. Tsirkin <mst@redhat.com>
Date: Wed, 14 May 2014 08:31:36 +0200
Subject: [PATCH 09/31] virtio-net: fix buffer overflow on invalid state load

RH-Author: Michael S. Tsirkin <mst@redhat.com>
Message-id: <1400056285-6688-1-git-send-email-mst@redhat.com>
Patchwork-id: 58855
O-Subject: [PATCH qemu-kvm RHEL7.1] virtio-net: fix buffer overflow on invalid state load
Bugzilla: 1095678
RH-Acked-by: Dr. David Alan Gilbert (git) <dgilbert@redhat.com>
RH-Acked-by: Xiao Wang <jasowang@redhat.com>
RH-Acked-by: Amos Kong <akong@redhat.com>

CVE-2013-4148 QEMU 1.0 integer conversion in
virtio_net_load()@hw/net/virtio-net.c

Deals with loading a corrupted savevm image.

>         n->mac_table.in_use = qemu_get_be32(f);

in_use is int so it can get negative when assigned 32bit unsigned value.

>         /* MAC_TABLE_ENTRIES may be different from the saved image */
>         if (n->mac_table.in_use <= MAC_TABLE_ENTRIES) {

passing this check ^^^

>             qemu_get_buffer(f, n->mac_table.macs,
>                             n->mac_table.in_use * ETH_ALEN);

with good in_use value, "n->mac_table.in_use * ETH_ALEN" can get
positive and bigger than mac_table.macs. For example 0x81000000
satisfies this condition when ETH_ALEN is 6.

Fix it by making the value unsigned.
For consistency, change first_multi as well.

Note: all call sites were audited to confirm that
making them unsigned didn't cause any issues:
it turns out we actually never do math on them,
so it's easy to validate because both values are
always <= MAC_TABLE_ENTRIES.

Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
(cherry picked from commit 71f7fe48e10a8437c9d42d859389f37157f59980)

Bugzilla: 1095678
Tested: on developer's box
Brew build: http://brewweb.devel.redhat.com/brew/taskinfo?taskID=7452039
---
 include/hw/virtio/virtio-net.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 include/hw/virtio/virtio-net.h |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h
index 75723a8..a02fc50 100644
--- a/include/hw/virtio/virtio-net.h
+++ b/include/hw/virtio/virtio-net.h
@@ -174,8 +174,8 @@ typedef struct VirtIONet {
     uint8_t nobcast;
     uint8_t vhost_started;
     struct {
-        int in_use;
-        int first_multi;
+        uint32_t in_use;
+        uint32_t first_multi;
         uint8_t multi_overflow;
         uint8_t uni_overflow;
         uint8_t *macs;
-- 
1.7.1