rxrpc: Fix variable overwrite

Values assigned to both variable resend_at and ack_at are overwritten
before they can be used.

The correct fix here is to add 'now' to the previously computed value in
resend_at and ack_at.

Addresses-Coverity-ID: 1462262
Addresses-Coverity-ID: 1462263
Addresses-Coverity-ID: 1462264
Fixes: beb8e5e4 ("rxrpc: Express protocol timeouts in terms of RTT")
Link: https://marc.info/?i=17004.1511808959%40warthog.procyon.org.ukSigned-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Signed-off-by: David Howells <dhowells@redhat.com>

net/rxrpc/call_event.c

@@ -123,7 +123,7 @@ static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason,
 		else
 			ack_at = expiry;
 
-		ack_at = jiffies + expiry;
+		ack_at += now;
 		if (time_before(ack_at, call->ack_at)) {
 			WRITE_ONCE(call->ack_at, ack_at);
 			rxrpc_reduce_call_timer(call, ack_at, now,

net/rxrpc/sendmsg.c

@@ -233,7 +233,7 @@ static void rxrpc_queue_packet(struct rxrpc_sock *rx, struct rxrpc_call *call,
 		if (resend_at < 1)
 			resend_at = 1;
 
-		resend_at = now + rxrpc_resend_timeout;
+		resend_at += now;
 		WRITE_ONCE(call->resend_at, resend_at);
 		rxrpc_reduce_call_timer(call, resend_at, now,
 					rxrpc_timer_set_for_send);