tcp: avoid possible arithmetic overflows
icsk_rto is a 32bit field, and icsk_backoff can reach 15 by default,
or more if some sysctl (eg tcp_retries2) are changed.
Better use 64bit to perform icsk_rto << icsk_backoff operations
As Joe Perches suggested, add a helper for this.
Yuchung spotted the tcp_v4_err() case.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 006b045..3b2e49cb 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -430,9 +430,9 @@
break;
icsk->icsk_backoff--;
- inet_csk(sk)->icsk_rto = (tp->srtt_us ? __tcp_set_rto(tp) :
- TCP_TIMEOUT_INIT) << icsk->icsk_backoff;
- tcp_bound_rto(sk);
+ icsk->icsk_rto = tp->srtt_us ? __tcp_set_rto(tp) :
+ TCP_TIMEOUT_INIT;
+ icsk->icsk_rto = inet_csk_rto_backoff(icsk, TCP_RTO_MAX);
skb = tcp_write_queue_head(sk);
BUG_ON(!skb);
