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virtio: add check for descriptor's mapped address

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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>
This commit is contained in:
Prasad J Pandit 2016-09-19 23:55:45 +05:30 committed by Michael S. Tsirkin
parent 9294d76c15
commit 973e7170dd
1 changed files with 5 additions and 0 deletions
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5
hw/virtio/virtio.c
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@ -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;