From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756543Ab3CZXoK (ORCPT ); Tue, 26 Mar 2013 19:44:10 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:52407 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754475Ab3CZWnv (ORCPT ); Tue, 26 Mar 2013 18:43:51 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, dormando , Eric Dumazet , "David S. Miller" Subject: [ 21/98] tcp: dont handle MTU reduction on LISTEN socket Date: Tue, 26 Mar 2013 15:42:10 -0700 Message-Id: <20130326224244.684801566@linuxfoundation.org> X-Mailer: git-send-email 1.8.1.rc1.5.g7e0651a In-Reply-To: <20130326224242.449070940@linuxfoundation.org> References: <20130326224242.449070940@linuxfoundation.org> User-Agent: quilt/0.60-5.1.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.8-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit 0d4f0608619de59fd8169dd8e72aadc28d80e715 ] When an ICMP ICMP_FRAG_NEEDED (or ICMPV6_PKT_TOOBIG) message finds a LISTEN socket, and this socket is currently owned by the user, we set TCP_MTU_REDUCED_DEFERRED flag in listener tsq_flags. This is bad because if we clone the parent before it had a chance to clear the flag, the child inherits the tsq_flags value, and next tcp_release_cb() on the child will decrement sk_refcnt. Result is that we might free a live TCP socket, as reported by Dormando. IPv4: Attempt to release TCP socket in state 1 Fix this issue by testing sk_state against TCP_LISTEN early, so that we set TCP_MTU_REDUCED_DEFERRED on appropriate sockets (not a LISTEN one) This bug was introduced in commit 563d34d05786 (tcp: dont drop MTU reduction indications) Reported-by: dormando Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp_ipv4.c | 14 +++++++------- net/ipv6/tcp_ipv6.c | 7 +++++++ 2 files changed, 14 insertions(+), 7 deletions(-) --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -274,13 +274,6 @@ static void tcp_v4_mtu_reduced(struct so struct inet_sock *inet = inet_sk(sk); u32 mtu = tcp_sk(sk)->mtu_info; - /* We are not interested in TCP_LISTEN and open_requests (SYN-ACKs - * send out by Linux are always <576bytes so they should go through - * unfragmented). - */ - if (sk->sk_state == TCP_LISTEN) - return; - dst = inet_csk_update_pmtu(sk, mtu); if (!dst) return; @@ -408,6 +401,13 @@ void tcp_v4_err(struct sk_buff *icmp_skb goto out; if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */ + /* We are not interested in TCP_LISTEN and open_requests + * (SYN-ACKs send out by Linux are always <576bytes so + * they should go through unfragmented). + */ + if (sk->sk_state == TCP_LISTEN) + goto out; + tp->mtu_info = info; if (!sock_owned_by_user(sk)) { tcp_v4_mtu_reduced(sk); --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -389,6 +389,13 @@ static void tcp_v6_err(struct sk_buff *s } if (type == ICMPV6_PKT_TOOBIG) { + /* We are not interested in TCP_LISTEN and open_requests + * (SYN-ACKs send out by Linux are always <576bytes so + * they should go through unfragmented). + */ + if (sk->sk_state == TCP_LISTEN) + goto out; + tp->mtu_info = ntohl(info); if (!sock_owned_by_user(sk)) tcp_v6_mtu_reduced(sk);