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From f1344659fd93ea0dfb9d8d1af25993e57584c773 Mon Sep 17 00:00:00 2001
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From: "Michael S. Tsirkin" <mst@redhat.com>
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Date: Thu, 3 Apr 2014 19:51:53 +0300
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Subject: [PATCH] virtio: validate num_sg when mapping
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CVE-2013-4535
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CVE-2013-4536
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Both virtio-block and virtio-serial read,
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VirtQueueElements are read in as buffers, and passed to
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virtqueue_map_sg(), where num_sg is taken from the wire and can force
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writes to indicies beyond VIRTQUEUE_MAX_SIZE.
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To fix, validate num_sg.
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Reported-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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Cc: Amit Shah <amit.shah@redhat.com>
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Signed-off-by: Juan Quintela <quintela@redhat.com>
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(cherry picked from commit 36cf2a37132c7f01fa9adb5f95f5312b27742fd4)
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---
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hw/virtio/virtio.c | 6 ++++++
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1 file changed, 6 insertions(+)
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diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
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index 0072542..a70169a 100644
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--- a/hw/virtio/virtio.c
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+++ b/hw/virtio/virtio.c
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@@ -430,6 +430,12 @@ void virtqueue_map_sg(struct iovec *sg, hwaddr *addr,
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unsigned int i;
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hwaddr len;
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+ if (num_sg >= VIRTQUEUE_MAX_SIZE) {
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+ error_report("virtio: map attempt out of bounds: %zd > %d",
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+ num_sg, VIRTQUEUE_MAX_SIZE);
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+ exit(1);
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+ }
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+
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for (i = 0; i < num_sg; i++) {
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len = sg[i].iov_len;
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sg[i].iov_base = cpu_physical_memory_map(addr[i], &len, is_write);
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