Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753635AbbDZOQO (ORCPT ); Sun, 26 Apr 2015 10:16:14 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:41129 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752643AbbDZOQK (ORCPT ); Sun, 26 Apr 2015 10:16:10 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Michal Kubecek , Eric Dumazet , "David S. Miller" Subject: [PATCH 3.19 01/27] tcp: prevent fetching dst twice in early demux code Date: Sun, 26 Apr 2015 16:15:32 +0200 Message-Id: <20150426134603.427305307@linuxfoundation.org> X-Mailer: git-send-email 2.3.6 In-Reply-To: <20150426134603.371719585@linuxfoundation.org> References: <20150426134603.371719585@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2117 Lines: 62 3.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: =?UTF-8?q?Michal=20Kube=C4=8Dek?= [ Upstream commit d0c294c53a771ae7e84506dfbd8c18c30f078735 ] On s390x, gcc 4.8 compiles this part of tcp_v6_early_demux() struct dst_entry *dst = sk->sk_rx_dst; if (dst) dst = dst_check(dst, inet6_sk(sk)->rx_dst_cookie); to code reading sk->sk_rx_dst twice, once for the test and once for the argument of ip6_dst_check() (dst_check() is inline). This allows ip6_dst_check() to be called with null first argument, causing a crash. Protect sk->sk_rx_dst access by READ_ONCE() both in IPv4 and IPv6 TCP early demux code. Fixes: 41063e9dd119 ("ipv4: Early TCP socket demux.") Fixes: c7109986db3c ("ipv6: Early TCP socket demux") Signed-off-by: Michal Kubecek Acked-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp_ipv4.c | 2 +- net/ipv6/tcp_ipv6.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1516,7 +1516,7 @@ void tcp_v4_early_demux(struct sk_buff * skb->sk = sk; skb->destructor = sock_edemux; if (sk->sk_state != TCP_TIME_WAIT) { - struct dst_entry *dst = sk->sk_rx_dst; + struct dst_entry *dst = READ_ONCE(sk->sk_rx_dst); if (dst) dst = dst_check(dst, 0); --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1583,7 +1583,7 @@ static void tcp_v6_early_demux(struct sk skb->sk = sk; skb->destructor = sock_edemux; if (sk->sk_state != TCP_TIME_WAIT) { - struct dst_entry *dst = sk->sk_rx_dst; + struct dst_entry *dst = READ_ONCE(sk->sk_rx_dst); if (dst) dst = dst_check(dst, inet6_sk(sk)->rx_dst_cookie); -- 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/