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[1/2] net: Fix announce_self

Message ID 20250117111709.970789-2-lvivier@redhat.com (mailing list archive)
State New
Headers show
Series net: Fix announce_self with vhost | expand

Commit Message

Laurent Vivier Jan. 17, 2025, 11:17 a.m. UTC 
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 <xiaohli@redhat.com>
Bug: https://issues.redhat.com/browse/RHEL-73891
Fixes: b9ad513e1876 ("net: Remove receive_raw()")
Cc: akihiko.odaki@daynix.com
Signed-off-by: Laurent Vivier <lvivier@redhat.com>
---
 net/net.c | 1 +
 1 file changed, 1 insertion(+)
diff mbox series

Patch

diff --git a/net/net.c b/net/net.c
index c1bb19a52373..9cded70dde74 100644
--- a/net/net.c
+++ b/net/net.c
@@ -822,6 +822,7 @@  static ssize_t qemu_deliver_packet_iov(NetClientState *sender,
         iov_copy[0].iov_len =  nc->vnet_hdr_len;
         memcpy(&iov_copy[1], iov, iovcnt * sizeof(*iov));
         iov = iov_copy;
+        iovcnt++;
     }
 
     if (nc->info->receive_iov) {