From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9D30EC433FE for ; Wed, 5 Oct 2022 19:29:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231267AbiJET23 (ORCPT ); Wed, 5 Oct 2022 15:28:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51150 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230234AbiJET2E (ORCPT ); Wed, 5 Oct 2022 15:28:04 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2C6C42CE2E for ; Wed, 5 Oct 2022 12:28:03 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id DA358B81F2D for ; Wed, 5 Oct 2022 19:28:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 33899C433D6; Wed, 5 Oct 2022 19:28:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1664998080; bh=w8qLDQG7LAM+h+Wjop64rA2JGBRFHfVRe+zsh39tVCk=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=mSOng3B0sUWzgfznq3oTAJNoDcpqFbmhxkbCmaOHuOv1aKVhB1+Ysnt4V4p1rgw6d QwetIxf7grj2XaWLYSYKPzL6HAWIYzNb7XSDg0P7DzbLXVDhBiswxfy4A6s/Y3XiaY zD9WtMKMfxEvA5MyvLbyC5l+TTBtnOn+I3gW0vqGSuc4lGC3UtONTh+igH7ms8jO/i E5To9CBxV1qFmH/22JcZACIw+awGQIFqAmPf9ZTGUAEn0LpIsU2nb3usKZaw0XMb0p TeaNv33IPsaFnunbsEmLTCZ78bKcxg/DwhMWByFcTd2aSGe0RctENoAScnHJtx3oT4 BtbGijrGYq9yQ== Message-ID: <84202713-ec7c-1e5e-8d9f-d36e715c81e4@kernel.org> Date: Wed, 5 Oct 2022 13:27:59 -0600 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.13.1 Subject: Re: [PATCH net] ipv4: Handle attempt to delete multipath route when fib_info contains an nh reference Content-Language: en-US To: Ido Schimmel Cc: kuba@kernel.org, davem@davemloft.net, pabeni@redhat.com, netdev@vger.kernel.org, Gwangun Jung References: <20221005181257.8897-1-dsahern@kernel.org> From: David Ahern In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 10/5/22 1:08 PM, Ido Schimmel wrote: > On Wed, Oct 05, 2022 at 12:12:57PM -0600, David Ahern wrote: >> Gwangun Jung reported a slab-out-of-bounds access in fib_nh_match: >> fib_nh_match+0xf98/0x1130 linux-6.0-rc7/net/ipv4/fib_semantics.c:961 >> fib_table_delete+0x5f3/0xa40 linux-6.0-rc7/net/ipv4/fib_trie.c:1753 >> inet_rtm_delroute+0x2b3/0x380 linux-6.0-rc7/net/ipv4/fib_frontend.c:874 >> >> Separate nexthop objects are mutually exclusive with the legacy >> multipath spec. Fix fib_nh_match to return if the config for the >> to be deleted route contains a multipath spec while the fib_info >> is using a nexthop object. > > Cool bug... Managed to reproduce with: > > # ip nexthop add id 1 blackhole > # ip route add 192.0.2.0/24 nhid 1 > # ip route del 192.0.2.0/24 nexthop via 198.51.100.1 nexthop via 198.51.100.2 that's what I did as well. > > Maybe add to tools/testing/selftests/net/fib_nexthops.sh ? I have one in my tree, but in my tests nothing blew up or threw an error message. It requires KASAN to be enabled otherwise the test does not trigger anything. > > Checked IPv6 and I don't think we can hit it there, but I will double > check tomorrow morning. > >> >> Fixes: 493ced1ac47c ("ipv4: Allow routes to use nexthop objects") >> Reported-by: Gwangun Jung >> Signed-off-by: David Ahern >> --- >> net/ipv4/fib_semantics.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> > > There is already such a check above for the non-multipath check, maybe > we can just move it up to cover both cases? Something like: > > diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c > index 2dc97583d279..e9a7f70a54df 100644 > --- a/net/ipv4/fib_semantics.c > +++ b/net/ipv4/fib_semantics.c > @@ -888,13 +888,13 @@ int fib_nh_match(struct net *net, struct fib_config *cfg, struct fib_info *fi, > return 1; > } > > + /* cannot match on nexthop object attributes */ > + if (fi->nh) > + return 1; that should work as well. I went with the simplest change that would definitely not have a negative impact on backports. > + > if (cfg->fc_oif || cfg->fc_gw_family) { > struct fib_nh *nh; > > - /* cannot match on nexthop object attributes */ > - if (fi->nh) > - return 1; > - > nh = fib_info_nh(fi, 0); > if (cfg->fc_encap) { > if (fib_encap_match(net, cfg->fc_encap_type,