Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030344AbaGCJYP (ORCPT ); Thu, 3 Jul 2014 05:24:15 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:52304 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030319AbaGCJYJ (ORCPT ); Thu, 3 Jul 2014 05:24:09 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Eric Dumazet , "David S. Miller" , Luis Henriques Subject: [PATCH 3.11 140/198] net: fix inet_getid() and ipv6_select_ident() bugs Date: Thu, 3 Jul 2014 10:19:43 +0100 Message-Id: <1404379241-8590-141-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1404379241-8590-1-git-send-email-luis.henriques@canonical.com> References: <1404379241-8590-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.11 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.11.10.13 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet commit 39c36094d78c39e038c1e499b2364e13bce36f54 upstream. 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 [ luis: backported to 3.11: used davem's backport for 3.10 ] Signed-off-by: Luis Henriques --- include/net/inetpeer.h | 9 +-------- net/ipv6/output_core.c | 11 +++-------- 2 files changed, 4 insertions(+), 16 deletions(-) diff --git a/include/net/inetpeer.h b/include/net/inetpeer.h index 53f464d7cddc..6ca347a0717e 100644 --- a/include/net/inetpeer.h +++ b/include/net/inetpeer.h @@ -178,16 +178,9 @@ static inline void inet_peer_refcheck(const struct inet_peer *p) /* 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 */ diff --git a/net/ipv6/output_core.c b/net/ipv6/output_core.c index ab92a3673fbb..39f6ad1629ff 100644 --- a/net/ipv6/output_core.c +++ b/net/ipv6/output_core.c @@ -9,7 +9,7 @@ void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt) { static atomic_t ipv6_fragmentation_id; - int old, new; + int ident; #if IS_ENABLED(CONFIG_IPV6) if (rt && !(rt->dst.flags & DST_NOPEER)) { @@ -25,13 +25,8 @@ void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt) } } #endif - 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); } EXPORT_SYMBOL(ipv6_select_ident); -- 1.9.1 -- 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/