From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , "David S. Miller" Subject: [PATCH 4.4 51/60] tcp: fix wraparound issue in tcp_lp Date: Thu, 11 May 2017 16:13:14 +0200 Message-Id: <20170511141239.234431479@linuxfoundation.org> In-Reply-To: <20170511141237.094835992@linuxfoundation.org> References: <20170511141237.094835992@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit a9f11f963a546fea9144f6a6d1a307e814a387e7 ] 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 Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- 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))