On Fri, Jan 17, 2025 at 7:17 PM Laurent Vivier <lviv...@redhat.com> wrote:
>
> b9ad513e1876 ("net: Remove receive_raw()") adds an iovec entry
> in qemu_deliver_packet_iov() to add the virtio-net header
> in the data when QEMU_NET_PACKET_FLAG_RAW is set but forgets
> to increase the number of iovec entries in the array, so
> receive_iov() will only send the first entry (the virtio-net
> entry, full of 0) and no data. The packet will be discarded.
>
> The only user of QEMU_NET_PACKET_FLAG_RAW is announce_self.
>
> We can see the problem with tcpdump:
>
> - QEMU parameters:
>
> .. -monitor stdio \
> -netdev bridge,id=netdev0,br=virbr0 \
> -device virtio-net,mac=9a:2b:2c:2d:2e:2f,netdev=netdev0 \
>
> - HMP command:
>
> (qemu) announce_self
>
> - TCP dump:
>
> $ sudo tcpdump -nxi virbr0
>
> without the fix:
>
> <nothing>
>
> with the fix:
>
> ARP, Reverse Request who-is 9a:2b:2c:2d:2e:2f tell 9a:2b:2c:2d:2e:2f,
> length 46
> 0x0000: 0001 0800 0604 0003 9a2b 2c2d 2e2f 0000
> 0x0010: 0000 9a2b 2c2d 2e2f 0000 0000 0000 0000
> 0x0020: 0000 0000 0000 0000 0000 0000 0000
>
> Reported-by: Xiaohui Li <xiao...@redhat.com>
> Bug: https://issues.redhat.com/browse/RHEL-73891
> Fixes: b9ad513e1876 ("net: Remove receive_raw()")
> Cc: akihiko.od...@daynix.com
> Signed-off-by: Laurent Vivier <lviv...@redhat.com>
> ---
Acked-by: Jason Wang <jasow...@redhat.com>
Thanks
