Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754941AbaLEXeL (ORCPT ); Fri, 5 Dec 2014 18:34:11 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:54229 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753183AbaLEW4E (ORCPT ); Fri, 5 Dec 2014 17:56:04 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, bill bonaparte , Jesper Dangaard Brouer , Pablo Neira Ayuso Subject: [PATCH 3.17 122/122] netfilter: conntrack: fix race in __nf_conntrack_confirm against get_next_corpse Date: Fri, 5 Dec 2014 14:44:56 -0800 Message-Id: <20141205223324.613437397@linuxfoundation.org> X-Mailer: git-send-email 2.1.3 In-Reply-To: <20141205223305.514276242@linuxfoundation.org> References: <20141205223305.514276242@linuxfoundation.org> User-Agent: quilt/0.63-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.17-stable review patch. If anyone has any objections, please let me know. ------------------ From: bill bonaparte commit 5195c14c8b27cc0b18220ddbf0e5ad3328a04187 upstream. After removal of the central spinlock nf_conntrack_lock, in commit 93bb0ceb75be2 ("netfilter: conntrack: remove central spinlock nf_conntrack_lock"), it is possible to race against get_next_corpse(). The race is against the get_next_corpse() cleanup on the "unconfirmed" list (a per-cpu list with seperate locking), which set the DYING bit. Fix this race, in __nf_conntrack_confirm(), by removing the CT from unconfirmed list before checking the DYING bit. In case race occured, re-add the CT to the dying list. While at this, fix coding style of the comment that has been updated. Fixes: 93bb0ceb75be2 ("netfilter: conntrack: remove central spinlock nf_conntrack_lock") Reported-by: bill bonaparte Signed-off-by: bill bonaparte Signed-off-by: Jesper Dangaard Brouer Signed-off-by: Pablo Neira Ayuso Signed-off-by: Greg Kroah-Hartman --- net/netfilter/nf_conntrack_core.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -611,12 +611,16 @@ __nf_conntrack_confirm(struct sk_buff *s */ NF_CT_ASSERT(!nf_ct_is_confirmed(ct)); pr_debug("Confirming conntrack %p\n", ct); - /* We have to check the DYING flag inside the lock to prevent - a race against nf_ct_get_next_corpse() possibly called from - user context, else we insert an already 'dead' hash, blocking - further use of that particular connection -JM */ + + /* We have to check the DYING flag after unlink to prevent + * a race against nf_ct_get_next_corpse() possibly called from + * user context, else we insert an already 'dead' hash, blocking + * further use of that particular connection -JM. + */ + nf_ct_del_from_dying_or_unconfirmed_list(ct); if (unlikely(nf_ct_is_dying(ct))) { + nf_ct_add_to_dying_list(ct); nf_conntrack_double_unlock(hash, reply_hash); local_bh_enable(); return NF_ACCEPT; @@ -636,8 +640,6 @@ __nf_conntrack_confirm(struct sk_buff *s zone == nf_ct_zone(nf_ct_tuplehash_to_ctrack(h))) goto out; - nf_ct_del_from_dying_or_unconfirmed_list(ct); - /* Timer relative to confirmation time, not original setting time, otherwise we'd get timer wrap in weird delay cases. */ -- 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/