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Blame 0023-virtio-net-out-of-bounds-buffer-write-on-load.patch

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From 1a29e58f9f23846d0e105a3157629786fc624f65 Mon Sep 17 00:00:00 2001
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From: "Michael S. Tsirkin" <mst@redhat.com>
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Date: Mon, 28 Apr 2014 16:08:21 +0300
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Subject: [PATCH] virtio-net: out-of-bounds buffer write on load
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CVE-2013-4149 QEMU 1.3.0 out-of-bounds buffer write in
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virtio_net_load()@hw/net/virtio-net.c
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>         } else if (n->mac_table.in_use) {
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>             uint8_t *buf = g_malloc0(n->mac_table.in_use);
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We are allocating buffer of size n->mac_table.in_use
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>             qemu_get_buffer(f, buf, n->mac_table.in_use * ETH_ALEN);
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and read to the n->mac_table.in_use size buffer n->mac_table.in_use *
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ETH_ALEN bytes, corrupting memory.
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If adversary controls state then memory written there is controlled
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by adversary.
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Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>
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Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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Signed-off-by: Juan Quintela <quintela@redhat.com>
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(cherry picked from commit 98f93ddd84800f207889491e0b5d851386b459cf)
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---
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 hw/net/virtio-net.c | 15 +++++++++++----
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 1 file changed, 11 insertions(+), 4 deletions(-)
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diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
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index 0a8cb40..940a7cf 100644
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--- a/hw/net/virtio-net.c
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+++ b/hw/net/virtio-net.c
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@@ -1362,10 +1362,17 @@ static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
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         if (n->mac_table.in_use <= MAC_TABLE_ENTRIES) {
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             qemu_get_buffer(f, n->mac_table.macs,
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                             n->mac_table.in_use * ETH_ALEN);
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-        } else if (n->mac_table.in_use) {
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-            uint8_t *buf = g_malloc0(n->mac_table.in_use);
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-            qemu_get_buffer(f, buf, n->mac_table.in_use * ETH_ALEN);
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-            g_free(buf);
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+        } else {
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+            int64_t i;
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+
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+            /* Overflow detected - can happen if source has a larger MAC table.
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+             * We simply set overflow flag so there's no need to maintain the
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+             * table of addresses, discard them all.
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+             * Note: 64 bit math to avoid integer overflow.
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+             */
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+            for (i = 0; i < (int64_t)n->mac_table.in_use * ETH_ALEN; ++i) {
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+                qemu_get_byte(f);
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+            }
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             n->mac_table.multi_overflow = n->mac_table.uni_overflow = 1;
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             n->mac_table.in_use = 0;
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         }