Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756269AbbGOKO6 (ORCPT ); Wed, 15 Jul 2015 06:14:58 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:44788 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752277AbbGOJNT (ORCPT ); Wed, 15 Jul 2015 05:13:19 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Eric Dumazet , Ying Xue , Julian Anastasov , "David S. Miller" , Luis Henriques Subject: [PATCH 3.16.y-ckt 010/185] neigh: do not modify unlinked entries Date: Wed, 15 Jul 2015 10:10:05 +0100 Message-Id: <1436951580-15977-11-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1436951580-15977-1-git-send-email-luis.henriques@canonical.com> References: <1436951580-15977-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3037 Lines: 89 3.16.7-ckt15 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Julian Anastasov commit 2c51a97f76d20ebf1f50fef908b986cb051fdff9 upstream. The lockless lookups can return entry that is unlinked. Sometimes they get reference before last neigh_cleanup_and_release, sometimes they do not need reference. Later, any modification attempts may result in the following problems: 1. entry is not destroyed immediately because neigh_update can start the timer for dead entry, eg. on change to NUD_REACHABLE state. As result, entry lives for some time but is invisible and out of control. 2. __neigh_event_send can run in parallel with neigh_destroy while refcnt=0 but if timer is started and expired refcnt can reach 0 for second time leading to second neigh_destroy and possible crash. Thanks to Eric Dumazet and Ying Xue for their work and analyze on the __neigh_event_send change. Fixes: 767e97e1e0db ("neigh: RCU conversion of struct neighbour") Fixes: a263b3093641 ("ipv4: Make neigh lookups directly in output packet path.") Fixes: 6fd6ce2056de ("ipv6: Do not depend on rt->n in ip6_finish_output2().") Cc: Eric Dumazet Cc: Ying Xue Signed-off-by: Julian Anastasov Acked-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Luis Henriques --- net/core/neighbour.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/net/core/neighbour.c b/net/core/neighbour.c index ef31fef25e5a..2b0d99dad8be 100644 --- a/net/core/neighbour.c +++ b/net/core/neighbour.c @@ -977,6 +977,8 @@ int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb) rc = 0; if (neigh->nud_state & (NUD_CONNECTED | NUD_DELAY | NUD_PROBE)) goto out_unlock_bh; + if (neigh->dead) + goto out_dead; if (!(neigh->nud_state & (NUD_STALE | NUD_INCOMPLETE))) { if (NEIGH_VAR(neigh->parms, MCAST_PROBES) + @@ -1033,6 +1035,13 @@ out_unlock_bh: write_unlock(&neigh->lock); local_bh_enable(); return rc; + +out_dead: + if (neigh->nud_state & NUD_STALE) + goto out_unlock_bh; + write_unlock_bh(&neigh->lock); + kfree_skb(skb); + return 1; } EXPORT_SYMBOL(__neigh_event_send); @@ -1096,6 +1105,8 @@ int neigh_update(struct neighbour *neigh, const u8 *lladdr, u8 new, if (!(flags & NEIGH_UPDATE_F_ADMIN) && (old & (NUD_NOARP | NUD_PERMANENT))) goto out; + if (neigh->dead) + goto out; if (!(new & NUD_VALID)) { neigh_del_timer(neigh); @@ -1245,6 +1256,8 @@ EXPORT_SYMBOL(neigh_update); */ void __neigh_set_probe_once(struct neighbour *neigh) { + if (neigh->dead) + return; neigh->updated = jiffies; if (!(neigh->nud_state & NUD_FAILED)) return; -- 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/