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virtio-net: correct packet length math

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We were requesting too much when checking buffer
length: size already includes host header length.

Further, we should not exit if we get a packet that
is too long, since this might not be under control
of the guest. Just drop the packet.

Red Hat bz 591494

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Michael S. Tsirkin 2010-06-22 16:22:49 +03:00
parent a213ff63ea
commit 279a42535d
1 changed files with 28 additions and 13 deletions
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41
hw/virtio-net.c
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@ -528,17 +528,18 @@ static ssize_t virtio_net_receive(VLANClientState *nc, const uint8_t *buf, size_
{
VirtIONet *n = DO_UPCAST(NICState, nc, nc)->opaque;
struct virtio_net_hdr_mrg_rxbuf *mhdr = NULL;
size_t hdr_len, offset, i;
size_t guest_hdr_len, offset, i, host_hdr_len;
if (!virtio_net_can_receive(&n->nic->nc))
return -1;
/* hdr_len refers to the header we supply to the guest */
hdr_len = n->mergeable_rx_bufs ?
guest_hdr_len = n->mergeable_rx_bufs ?
sizeof(struct virtio_net_hdr_mrg_rxbuf) : sizeof(struct virtio_net_hdr);
if (!virtio_net_has_buffers(n, size + hdr_len))
host_hdr_len = n->has_vnet_hdr ? sizeof(struct virtio_net_hdr) : 0;
if (!virtio_net_has_buffers(n, size + guest_hdr_len - host_hdr_len))
return 0;
if (!receive_filter(n, buf, size))
@ -553,13 +554,14 @@ static ssize_t virtio_net_receive(VLANClientState *nc, const uint8_t *buf, size_
total = 0;
if ((i != 0 && !n->mergeable_rx_bufs) ||
virtqueue_pop(n->rx_vq, &elem) == 0) {
if (virtqueue_pop(n->rx_vq, &elem) == 0) {
if (i == 0)
return -1;
fprintf(stderr, "virtio-net truncating packet: "
"offset %zd, size %zd, hdr_len %zd\n",
offset, size, hdr_len);
fprintf(stderr, "virtio-net unexpected empty queue: "
"i %zd mergeable %d offset %zd, size %zd, "
"guest hdr len %zd, host hdr len %zd guest features 0x%x\n",
i, n->mergeable_rx_bufs, offset, size,
guest_hdr_len, host_hdr_len, n->vdev.guest_features);
exit(1);
}
@ -568,7 +570,7 @@ static ssize_t virtio_net_receive(VLANClientState *nc, const uint8_t *buf, size_
exit(1);
}
if (!n->mergeable_rx_bufs && elem.in_sg[0].iov_len != hdr_len) {
if (!n->mergeable_rx_bufs && elem.in_sg[0].iov_len != guest_hdr_len) {
fprintf(stderr, "virtio-net header not in first element\n");
exit(1);
}
@ -580,19 +582,32 @@ static ssize_t virtio_net_receive(VLANClientState *nc, const uint8_t *buf, size_
mhdr = (struct virtio_net_hdr_mrg_rxbuf *)sg[0].iov_base;
offset += receive_header(n, sg, elem.in_num,
buf + offset, size - offset, hdr_len);
total += hdr_len;
buf + offset, size - offset, guest_hdr_len);
total += guest_hdr_len;
}
/* copy in packet. ugh */
len = iov_from_buf(sg, elem.in_num,
buf + offset, size - offset);
total += len;
offset += len;
/* If buffers can't be merged, at this point we
* must have consumed the complete packet.
* Otherwise, drop it. */
if (!n->mergeable_rx_bufs && offset < size) {
#if 0
fprintf(stderr, "virtio-net truncated non-mergeable packet: "
"i %zd mergeable %d offset %zd, size %zd, "
"guest hdr len %zd, host hdr len %zd\n",
i, n->mergeable_rx_bufs,
offset, size, guest_hdr_len, host_hdr_len);
#endif
return size;
}
/* signal other side */
virtqueue_fill(n->rx_vq, &elem, total, i++);
offset += len;
}
if (mhdr)