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=-16.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 2354DC4338F for ; Fri, 6 Aug 2021 22:42:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EE78C61181 for ; Fri, 6 Aug 2021 22:42:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243706AbhHFWmz (ORCPT ); Fri, 6 Aug 2021 18:42:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:56046 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242484AbhHFWmo (ORCPT ); Fri, 6 Aug 2021 18:42:44 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 0DCC860EE7; Fri, 6 Aug 2021 22:42:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1628289748; bh=AXfG4bL+S5KpiWpdKgIENx9EqmoykkbhVX5F/NL+Vss=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=j8t+HZ56qH16mzBQSBeshmeB3gqT8o+jz8WjbYOPROwvGev0cbxvgGFiDTjNkZHJZ xwy7HN5vB9S20So7fNpTcE8M0pB9DE0osori9dkYh4vQeL5UGJmsetkhtzILB3HrR8 46Y3+KJrghpiDLvtaTD62AUgFbnBi9wtcbEmyncCAluPPQJD5B3BUOoo5k+ajzL7dc 5o5pL+EsozOPLGvCs3fcb0uKtzh7XMw4/D1jSXkCmMNY38qtATC/slMwIImUaLhZ0s UMRGUGTGi5mGaHUdHphG7bX19pkN9d4OiuSvnZlqdu601PhNZbhZVMPexrYcbn+eOv gS4vdSRUe+f5g== Date: Fri, 6 Aug 2021 15:42:27 -0700 From: Jakub Kicinski To: Vasily Averin Cc: "David S. Miller" , Hideaki YOSHIFUJI , David Ahern , Eric Dumazet , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@openvz.org, Julian Wiedmann Subject: Re: [PATCH NET] vrf: fix null pointer dereference in vrf_finish_output() Message-ID: <20210806154227.49ac089d@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> In-Reply-To: <5ba67c28-1056-e24d-cad3-4b7aaac01111@virtuozzo.com> References: <20210806.111412.1329682129695306949.davem@davemloft.net> <5ba67c28-1056-e24d-cad3-4b7aaac01111@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Fri, 6 Aug 2021 15:53:00 +0300 Vasily Averin wrote: > After 14ee70ca89e6 ("vrf: use skb_expand_head in vrf_finish_output") > skb->dev is accessed after skb free. > Let's replace skb->dev by dev = skb_dst(skb)->dev: > vrf_finish_output() is only called from vrf_output(), > it set skb->dev to skb_dst(skb)->dev and calls POSTROUTING netfilter > hooks, where output device should not be changed. > > Fixes: 14ee70ca89e6 ("vrf: use skb_expand_head in vrf_finish_output") > Reported-by: Julian Wiedmann > Signed-off-by: Vasily Averin Thanks for following up! I decided to pick a similar patch from Dan Carpenter [1] because the chunk quoted below is not really necessary. [1] https://lore.kernel.org/kernel-janitors/20210806150435.GB15586@kili/ > @@ -883,7 +883,7 @@ static int vrf_finish_output(struct net *net, struct sock *sk, struct sk_buff *s > } > > rcu_read_unlock_bh(); > - vrf_tx_error(skb->dev, skb); > + vrf_tx_error(dev, skb); > return -EINVAL; > } >