Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932685AbaGHTqz (ORCPT ); Tue, 8 Jul 2014 15:46:55 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:54056 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755660AbaGHTIi (ORCPT ); Tue, 8 Jul 2014 15:08:38 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "David S. Miller" , "Eric Dumazet" Date: Tue, 08 Jul 2014 20:01:50 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 112/125] net: fix inet_getid() and ipv6_select_ident() bugs In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.61-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit 39c36094d78c39e038c1e499b2364e13bce36f54 ] I noticed we were sending wrong IPv4 ID in TCP flows when MTU discovery is disabled. Note how GSO/TSO packets do not have monotonically incrementing ID. 06:37:41.575531 IP (id 14227, proto: TCP (6), length: 4396) 06:37:41.575534 IP (id 14272, proto: TCP (6), length: 65212) 06:37:41.575544 IP (id 14312, proto: TCP (6), length: 57972) 06:37:41.575678 IP (id 14317, proto: TCP (6), length: 7292) 06:37:41.575683 IP (id 14361, proto: TCP (6), length: 63764) It appears I introduced this bug in linux-3.1. inet_getid() must return the old value of peer->ip_id_count, not the new one. Lets revert this part, and remove the prevention of a null identification field in IPv6 Fragment Extension Header, which is dubious and not even done properly. Fixes: 87c48fa3b463 ("ipv6: make fragment identifications less predictable") Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings --- include/net/inetpeer.h | 9 +-------- net/ipv6/ip6_output.c | 11 +++-------- 2 files changed, 4 insertions(+), 16 deletions(-) --- a/include/net/inetpeer.h +++ b/include/net/inetpeer.h @@ -115,16 +115,9 @@ static inline void inet_peer_refcheck(co /* can be called with or without local BH being disabled */ static inline int inet_getid(struct inet_peer *p, int more) { - int old, new; more++; inet_peer_refcheck(p); - do { - old = atomic_read(&p->ip_id_count); - new = old + more; - if (!new) - new = 1; - } while (atomic_cmpxchg(&p->ip_id_count, old, new) != old); - return new; + return atomic_add_return(more, &p->ip_id_count) - more; } #endif /* _NET_INETPEER_H */ --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -612,7 +612,7 @@ int ip6_find_1stfragopt(struct sk_buff * void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt) { static atomic_t ipv6_fragmentation_id; - int old, new; + int ident; if (rt && !(rt->dst.flags & DST_NOPEER)) { struct inet_peer *peer; @@ -625,13 +625,8 @@ void ipv6_select_ident(struct frag_hdr * return; } } - do { - old = atomic_read(&ipv6_fragmentation_id); - new = old + 1; - if (!new) - new = 1; - } while (atomic_cmpxchg(&ipv6_fragmentation_id, old, new) != old); - fhdr->identification = htonl(new); + ident = atomic_inc_return(&ipv6_fragmentation_id); + fhdr->identification = htonl(ident); } int ip6_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) -- 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/