From 71f7fe48e10a8437c9d42d859389f37157f59980 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" 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 Signed-off-by: Michael S. Tsirkin Reviewed-by: Laszlo Ersek Signed-off-by: Juan Quintela --- 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 df60f16a3e..4b32440837 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;