virtio-net: fix buffer overflow on invalid state load
commit71f7fe48e10a8437c9d42d859389f37157f59980
authorMichael S. Tsirkin <mst@redhat.com>
Thu, 3 Apr 2014 16:50:39 +0000 (3 19:50 +0300)
committerJuan Quintela <quintela@redhat.com>
Mon, 5 May 2014 12:15:10 +0000 (5 14:15 +0200)
tree6984fa70c53fefbaa28af8e12f8456300e92f5a9
parent4082f0889ba04678fc14816c53e1b9251ea9207e
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>
include/hw/virtio/virtio-net.h