tcp: call tcp_rate_skb_sent() when retransmit with unaligned skb->data

Current implementation calls tcp_rate_skb_sent() when tcp_transmit_skb() is called when it clones skb only. Not calling tcp_rate_skb_sent() is OK for all such code paths except from __tcp_retransmit_skb() which happens when skb->data address is not aligned. This may rarely happen e.g. when small amount of data is sent initially and the receiver partially acks odd number of bytes for some reason, possibly malicious.

---
 net/ipv4/tcp_output.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

index 973befc36fd4..1151870018e3 100644
@@ -2843,8 +2843,10 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs)
 		nskb = __pskb_copy(skb, MAX_TCP_HEADER, GFP_ATOMIC);
 		err = nskb ? tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC) :
 			     -ENOBUFS;
-		if (!err)
+		if (!err) {
 			skb->skb_mstamp = tp->tcp_mstamp;
+			tcp_rate_skb_sent(sk, skb);
+		}
 	} else {
 		err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC);
 	}

2.15.0.rc0.271.g36b669edcc-goog

From: Yousuk Seung <[email protected]>
Date: Tue, 24 Oct 2017 16:44:42 -0700

This doesn't apply to any of m trees.