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virtio_ring: secure handling of mapping errors

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We should not depend on the DMA address, length and flag of descriptor
table since they could be wrote with arbitrary value by the device. So
this patch switches to use the stored one in desc_extra.

Note that the indirect descriptors are fine since they are read-only
streaming mappings.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210604055350.58753-5-jasowang@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Jason Wang 2021-06-04 13:53:47 +08:00 committed by Michael S. Tsirkin
parent 5a22242160
commit 44593865b7
1 changed files with 4 additions and 1 deletions
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5
drivers/virtio/virtio_ring.c
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@ -1219,13 +1219,16 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
unmap_release:
err_idx = i;
i = head;
curr = vq->free_head;
vq->packed.avail_used_flags = avail_used_flags;
for (n = 0; n < total_sg; n++) {
if (i == err_idx)
break;
vring_unmap_desc_packed(vq, &desc[i]);
vring_unmap_state_packed(vq,
&vq->packed.desc_extra[curr]);
curr = vq->packed.desc_extra[curr].next;
i++;
if (i >= vq->packed.vring.num)
i = 0;