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From 973e7170dddefb491a48df5cba33b2ae151013a0 Mon Sep 17 00:00:00 2001
From: Prasad J Pandit <pjp@fedoraproject.org>
Date: Mon, 19 Sep 2016 23:55:45 +0530
Subject: [PATCH] virtio: add check for descriptor's mapped address
virtio back end uses set of buffers to facilitate I/O operations.
If its size is too large, 'cpu_physical_memory_map' could return
a null address. This would result in a null dereference while
un-mapping descriptors. Add check to avoid it.
Reported-by: Qinghao Tang <luodalongde@gmail.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
---
hw/virtio/virtio.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index fcf3358d6c0d..bb656b1ccff0 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -495,6 +495,11 @@ static void virtqueue_map_desc(unsigned int *p_num_sg, hwaddr *addr, struct iove
}
iov[num_sg].iov_base = cpu_physical_memory_map(pa, &len, is_write);
+ if (!iov[num_sg].iov_base) {
+ error_report("virtio: bogus descriptor or out of resources");
+ exit(1);
+ }
+
iov[num_sg].iov_len = len;
addr[num_sg] = pa;
--
2.11.0
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