From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zhang Le Subject: [PATCH] ipv4: mitigate an integer underflow when comparing tcp timestamps Date: Sun, 14 Nov 2010 15:35:56 +0800 Message-ID: <1289720156-30118-1-git-send-email-r0bertz@gentoo.org> Cc: Zhang Le , "David S. Miller" , Alexey Kuznetsov , "Pekka Savola (ipv6)" , James Morris , Hideaki YOSHIFUJI , Patrick McHardy To: netdev@vger.kernel.org, linux-kernel@vger.kernel.org Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Behind a loadbalancer which does NAT, peer->tcp_ts could be much smaller than req->ts_recent. In this case, theoretically the req should not be ignored. But in fact, it could be ignored, if peer->tcp_ts is so small that the difference between this two number is larger than 2 to the power of 31. I understand that under this situation, timestamp does not make sense any more, because it actually comes from difference machines. However, if anyone ever need to do the same investigation which I have done, this will save some time for him. Signed-off-by: Zhang Le --- net/ipv4/tcp_ipv4.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 8f8527d..1eb4974 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1352,8 +1352,8 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb) peer->v4daddr == saddr) { inet_peer_refcheck(peer); if ((u32)get_seconds() - peer->tcp_ts_stamp < TCP_PAWS_MSL && - (s32)(peer->tcp_ts - req->ts_recent) > - TCP_PAWS_WINDOW) { + ((s32)(peer->tcp_ts - req->ts_recent) > TCP_PAWS_WINDOW && + peer->tcp_ts > req->ts_recent)) { NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSPASSIVEREJECTED); goto drop_and_release; } -- 1.7.3.2