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From: Prasad J Pandit <pjp@fedoraproject.org>
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Date: Mon, 19 Sep 2016 23:55:45 +0530
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Subject: [PATCH] virtio: add check for descriptor's mapped address
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virtio back end uses set of buffers to facilitate I/O operations.
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If its size is too large, 'cpu_physical_memory_map' could return
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a null address. This would result in a null dereference while
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un-mapping descriptors. Add check to avoid it.
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Reported-by: Qinghao Tang <luodalongde@gmail.com>
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Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
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Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
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Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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Reviewed-by: Laszlo Ersek <lersek@redhat.com>
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(cherry picked from commit 973e7170dddefb491a48df5cba33b2ae151013a0)
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---
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hw/virtio/virtio.c | 5 +++++
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1 file changed, 5 insertions(+)
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diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
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index 20c4f39..3a470fc 100644
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--- a/hw/virtio/virtio.c
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+++ b/hw/virtio/virtio.c
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@@ -472,6 +472,11 @@ static void virtqueue_map_desc(unsigned int *p_num_sg, hwaddr *addr, struct iove
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}
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iov[num_sg].iov_base = cpu_physical_memory_map(pa, &len, is_write);
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+ if (!iov[num_sg].iov_base) {
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+ error_report("virtio: bogus descriptor or out of resources");
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+ exit(1);
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+ }
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+
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iov[num_sg].iov_len = len;
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addr[num_sg] = pa;
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