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 X-Spam-Level: X-Spam-Status: No, score=-12.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0B253C07E9B for ; Wed, 7 Jul 2021 16:42:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E1BA161CCB for ; Wed, 7 Jul 2021 16:42:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230324AbhGGQpA (ORCPT ); Wed, 7 Jul 2021 12:45:00 -0400 Received: from mail.kernel.org ([198.145.29.99]:36456 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229519AbhGGQo7 (ORCPT ); Wed, 7 Jul 2021 12:44:59 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 2F96B61CC9; Wed, 7 Jul 2021 16:42:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1625676139; bh=p7JWEZZ5FyAZ7TfdKVc9jFwbgMkD0Zwgu/xDE16ibq8=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=p2lsV6uRzSOYznp5RCxMxmV5VKDFOZV1hVH0xAobKXWR77l40gM0ZkZs/2LjArsC4 S6Yeq/rzemP9/1x+/90+ri5znqSrB7v0onIBPRgipOziSeF0EdQeN6HTsQefyEP5cW +B7qXtSztUyP5ydIfmzD0S/k8L6+Ki88hsJh+h5wEZD6IRqO1zF85VSUd3ymjGYKDN 4oblNR7VdrBXlfM0QCIBqWZ7x/cZxRo76rAp9+h+byhd7SK2gnKSX84FeiZZxDLTQF JJXdjx0HkDdN5EIa6cz1EcDeG1kVQ225jNzLqooIZNaLM00ZGBptxy3unHi3kI5O3r 3NGRY1b2cY3sg== Date: Wed, 7 Jul 2021 09:42:18 -0700 From: Jakub Kicinski To: David Ahern Cc: Vasily Averin , "David S. Miller" , Hideaki YOSHIFUJI , David Ahern , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH IPV6 1/1] ipv6: allocate enough headroom in ip6_finish_output2() Message-ID: <20210707094218.0e9b6ffc@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> In-Reply-To: <8996db63-5554-d3dc-cd36-94570ade6d18@gmail.com> References: <3cb5a2e5-4e4c-728a-252d-4757b6c9612d@virtuozzo.com> <8996db63-5554-d3dc-cd36-94570ade6d18@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 7 Jul 2021 08:45:13 -0600 David Ahern wrote: > On 7/7/21 8:04 AM, Vasily Averin wrote: > > diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c > > index ff4f9eb..e5af740 100644 > > --- a/net/ipv6/ip6_output.c > > +++ b/net/ipv6/ip6_output.c > > @@ -61,9 +61,24 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff * > > struct dst_entry *dst = skb_dst(skb); > > struct net_device *dev = dst->dev; > > const struct in6_addr *nexthop; > > + unsigned int hh_len = LL_RESERVED_SPACE(dev); > > struct neighbour *neigh; > > int ret; > > > > + /* Be paranoid, rather than too clever. */ > > + if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) { > > + struct sk_buff *skb2; > > + > > + skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev)); > > why not use hh_len here? Is there a reason for the new skb? Why not pskb_expand_head()? > > + if (!skb2) { > > + kfree_skb(skb); > > + return -ENOMEM; > > + } > > + if (skb->sk) > > + skb_set_owner_w(skb2, skb->sk); > > + consume_skb(skb); > > + skb = skb2; > > + } > > if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr)) { > > struct inet6_dev *idev = ip6_dst_idev(skb_dst(skb));