Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754074AbaFWIr3 (ORCPT ); Mon, 23 Jun 2014 04:47:29 -0400 Received: from ip4-83-240-18-248.cust.nbox.cz ([83.240.18.248]:55557 "EHLO ip4-83-240-18-248.cust.nbox.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752596AbaFWIc3 (ORCPT ); Mon, 23 Jun 2014 04:32:29 -0400 From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Eric Dumazet , "David S. Miller" , Jiri Slaby Subject: [PATCH 3.12 097/111] net: fix inet_getid() and ipv6_select_ident() bugs Date: Mon, 23 Jun 2014 10:32:12 +0200 Message-Id: <12b4aba2d6f870dd8f505ae5dd5fc887d6484a93.1403512281.git.jslaby@suse.cz> X-Mailer: git-send-email 2.0.0 In-Reply-To: <55d5f044a1fc96a74e4470e318c0a24f27a9ab7e.1403512280.git.jslaby@suse.cz> References: <55d5f044a1fc96a74e4470e318c0a24f27a9ab7e.1403512280.git.jslaby@suse.cz> In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Eric Dumazet 3.12-stable review patch. If anyone has any objections, please let me know. =============== [ 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: Jiri Slaby --- 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 827f795209cf..b31a01263185 100644 --- a/net/ipv6/output_core.c +++ b/net/ipv6/output_core.c @@ -10,7 +10,7 @@ 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)) { @@ -26,13 +26,8 @@ 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); -- 2.0.0 -- 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/