From ea96c6a9c91da1923aa922a781fd7abbf9f51b6c Mon Sep 17 00:00:00 2001

From: "Michael S. Tsirkin" <mst@redhat.com>

Date: Thu, 3 Apr 2014 19:50:39 +0300

Subject: [PATCH] virtio-net: fix buffer overflow on invalid state load

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)

---

 include/hw/virtio/virtio-net.h | 4 ++--

 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h

index df60f16..4b32440 100644

--- a/include/hw/virtio/virtio-net.h

+++ b/include/hw/virtio/virtio-net.h

@@ -176,8 +176,8 @@ 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;