From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Ahern Subject: Re: [PATCH] ipv6: Fix idev->addr_list corruption Date: Mon, 10 Apr 2017 10:24:11 -0600 Message-ID: <590b8abc-93e3-f05e-bf63-5245a9860be1@cumulusnetworks.com> References: <1491806199-26115-1-git-send-email-rabin.vincent@axis.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, Rabin Vincent , Mike Manning To: Rabin Vincent , davem@davemloft.net Return-path: Received: from mail-pf0-f178.google.com ([209.85.192.178]:36265 "EHLO mail-pf0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752515AbdDJQYO (ORCPT ); Mon, 10 Apr 2017 12:24:14 -0400 Received: by mail-pf0-f178.google.com with SMTP id o126so35692277pfb.3 for ; Mon, 10 Apr 2017 09:24:14 -0700 (PDT) In-Reply-To: <1491806199-26115-1-git-send-email-rabin.vincent@axis.com> Sender: netdev-owner@vger.kernel.org List-ID: On 4/10/17 12:36 AM, Rabin Vincent wrote: > From: Rabin Vincent > > addrconf_ifdown() removes elements from the idev->addr_list without > holding the idev->lock. > > If this happens while the loop in __ipv6_dev_get_saddr() is handling the > same element, that function ends up in an infinite loop: > > NMI watchdog: BUG: soft lockup - CPU#1 stuck for 23s! [test:1719] > Call Trace: > ipv6_get_saddr_eval+0x13c/0x3a0 > __ipv6_dev_get_saddr+0xe4/0x1f0 > ipv6_dev_get_saddr+0x1b4/0x204 > ip6_dst_lookup_tail+0xcc/0x27c > ip6_dst_lookup_flow+0x38/0x80 > udpv6_sendmsg+0x708/0xba8 > sock_sendmsg+0x18/0x30 > SyS_sendto+0xb8/0xf8 > syscall_common+0x34/0x58 > > Fixes: 6a923934c33 (Revert "ipv6: Revert optional address flusing on ifdown.") > Signed-off-by: Rabin Vincent > --- > net/ipv6/addrconf.c | 11 +++++++---- > 1 file changed, 7 insertions(+), 4 deletions(-) > > diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c > index 3631725..80ce478 100644 > --- a/net/ipv6/addrconf.c > +++ b/net/ipv6/addrconf.c > @@ -3626,14 +3626,19 @@ static int addrconf_ifdown(struct net_device *dev, int how) > INIT_LIST_HEAD(&del_list); > list_for_each_entry_safe(ifa, tmp, &idev->addr_list, if_list) { > struct rt6_info *rt = NULL; > + bool keep; > > addrconf_del_dad_work(ifa); > > + keep = keep_addr && (ifa->flags & IFA_F_PERMANENT) && > + !addr_is_local(&ifa->addr); > + if (!keep) > + list_move(&ifa->if_list, &del_list); > + > write_unlock_bh(&idev->lock); yes, the list manipulation should be done under the idev->lock. thanks for fixing. Acked-by: David Ahern