| From: Eric Dumazet <edumazet@google.com> |
| Date: Mon, 1 May 2017 15:29:48 -0700 |
| Subject: tcp: fix wraparound issue in tcp_lp |
| |
| commit a9f11f963a546fea9144f6a6d1a307e814a387e7 upstream. |
| |
| Be careful when comparing tcp_time_stamp to some u32 quantity, |
| otherwise result can be surprising. |
| |
| Fixes: 7c106d7e782b ("[TCP]: TCP Low Priority congestion control") |
| Signed-off-by: Eric Dumazet <edumazet@google.com> |
| Signed-off-by: David S. Miller <davem@davemloft.net> |
| [bwh: Backported to 3.2: adjust context] |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| net/ipv4/tcp_lp.c | 6 ++++-- |
| 1 file changed, 4 insertions(+), 2 deletions(-) |
| |
| --- a/net/ipv4/tcp_lp.c |
| +++ b/net/ipv4/tcp_lp.c |
| @@ -264,13 +264,15 @@ static void tcp_lp_pkts_acked(struct soc |
| { |
| struct tcp_sock *tp = tcp_sk(sk); |
| struct lp *lp = inet_csk_ca(sk); |
| + u32 delta; |
| |
| if (rtt_us > 0) |
| tcp_lp_rtt_sample(sk, rtt_us); |
| |
| /* calc inference */ |
| - if (tcp_time_stamp > tp->rx_opt.rcv_tsecr) |
| - lp->inference = 3 * (tcp_time_stamp - tp->rx_opt.rcv_tsecr); |
| + delta = tcp_time_stamp - tp->rx_opt.rcv_tsecr; |
| + if ((s32)delta > 0) |
| + lp->inference = 3 * delta; |
| |
| /* test if within inference */ |
| if (lp->last_drop && (tcp_time_stamp - lp->last_drop < lp->inference)) |
