sctp: Do not reset the packet during sctp_packet_config().

sctp_packet_config() is called when getting the packet ready
for appending of chunks.  The function should not touch the
current state, since it's possible to ping-pong between two
transports when sending, and that can result packet corruption
followed by skb overlfow crash.

Reported-by: Thomas Dreibholz <dreibh@iem.uni-due.de>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/output.c

@@ -92,7 +92,6 @@ struct sctp_packet *sctp_packet_config(struct sctp_packet *packet,
 	SCTP_DEBUG_PRINTK("%s: packet:%p vtag:0x%x\n", __func__,
 			  packet, vtag);
 
-	sctp_packet_reset(packet);
 	packet->vtag = vtag;
 
 	if (ecn_capable && sctp_packet_empty(packet)) {