Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753997Ab0KNHgf (ORCPT ); Sun, 14 Nov 2010 02:36:35 -0500 Received: from mail-pz0-f46.google.com ([209.85.210.46]:58449 "EHLO mail-pz0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753614Ab0KNHgd (ORCPT ); Sun, 14 Nov 2010 02:36:33 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:from:to:cc:subject:date:message-id:x-mailer; b=PGzPAAagfF8Xm3+FG1apET4q53WnooZEtk4dI2p/XbBLdFKH2ABZnGPmoKy/rdjQBK UEU6ACz7fzrnLRJKtNHZdtYyOssM3VXetAi0AoxGQjFQRZDN6r8rgHt3hU/fyqj7JU1q PWGYR81GXwCXooVz6kdmCu4aqbzxyExrkt64k= From: Zhang Le To: netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Zhang Le , "David S. Miller" , Alexey Kuznetsov , "Pekka Savola (ipv6)" , James Morris , Hideaki YOSHIFUJI , Patrick McHardy 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> X-Mailer: git-send-email 1.7.3.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1569 Lines: 39 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/