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[Qemu-devel] Re: [PATCH] virtio-net: correct header length math
From: |
Juan Quintela |
Subject: |
[Qemu-devel] Re: [PATCH] virtio-net: correct header length math |
Date: |
Wed, 23 Jun 2010 17:57:13 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) |
"Michael S. Tsirkin" <address@hidden> wrote:
> We were requesting too much when checking buffer
> length: size already includes host header length.
>
> Signed-off-by: Michael S. Tsirkin <address@hidden>
All changes here are ok, but we are still missing more checks.
> ---
> hw/virtio-net.c | 20 +++++++++++---------
> 1 files changed, 11 insertions(+), 9 deletions(-)
>
> diff --git a/hw/virtio-net.c b/hw/virtio-net.c
> index 06ba481..2646c87 100644
> --- a/hw/virtio-net.c
> +++ b/hw/virtio-net.c
> @@ -527,17 +527,18 @@ 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);
>
>
nitpit: empty extra line
> - 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))
size is not used by receive_filter. We are assuming that size is at
least 16 + sizeof(struct virtio_net_hdr).
while (offset < size) {
we are still testing offset with size, but we read headers from there
also :(
Later, Juan.