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=-9.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT 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 B29AFC10F0E for ; Mon, 15 Apr 2019 19:09:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7EF27218A1 for ; Mon, 15 Apr 2019 19:09:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555355395; bh=sD7gOzUOKKzJwYA0BwrxQnGXaY0I4f2t1KjIDK1wUqk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=QOQ9yQ0zHc2vUEp3hERe+GUwJLveR3AGcZeP/wnCYsFamrgySRy687p3+shv8B01t 8M5FAUYwtSIbXzEg+bwzP/H2XWLKHA9seH/0gkKuvXtCp9uA/mwgCaPpeKA0ihPKon iDLMuSEq5g+QPYfda8vyzHHAxOj+ERWpwfbZ4o+Y= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730824AbfDOTJx (ORCPT ); Mon, 15 Apr 2019 15:09:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:45666 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729610AbfDOTJu (ORCPT ); Mon, 15 Apr 2019 15:09:50 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id CF1E820651; Mon, 15 Apr 2019 19:09:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555355390; bh=sD7gOzUOKKzJwYA0BwrxQnGXaY0I4f2t1KjIDK1wUqk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=1+JWY2ekMUDB6X89suEK3ivtpph/SLsf7BEX02r8lEEw8WnXANeF34aT0stP9b5AM KcT1UZaqfguyuljxa16gqtD4I5SEAzTRX0XZBkjvu8OM4dqQbFjxDFqjVYCIY7jJC+ r4nZrbsiqbR3yfRIbdJ/+ZR8w1T0VjkWo4T+nYMI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Junwei Hu , Wenhao Zhang , syzbot+e8ce541d095e486074fc@syzkaller.appspotmail.com, Zhiqiang Liu , Martin KaFai Lau , "David S. Miller" , Sasha Levin Subject: [PATCH 5.0 009/117] ipv6: Fix dangling pointer when ipv6 fragment Date: Mon, 15 Apr 2019 20:59:39 +0200 Message-Id: <20190415183745.361112272@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190415183744.887851196@linuxfoundation.org> References: <20190415183744.887851196@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [ Upstream commit ef0efcd3bd3fd0589732b67fb586ffd3c8705806 ] At the beginning of ip6_fragment func, the prevhdr pointer is obtained in the ip6_find_1stfragopt func. However, all the pointers pointing into skb header may change when calling skb_checksum_help func with skb->ip_summed = CHECKSUM_PARTIAL condition. The prevhdr pointe will be dangling if it is not reloaded after calling __skb_linearize func in skb_checksum_help func. Here, I add a variable, nexthdr_offset, to evaluate the offset, which does not changes even after calling __skb_linearize func. Fixes: 405c92f7a541 ("ipv6: add defensive check for CHECKSUM_PARTIAL skbs in ip_fragment") Signed-off-by: Junwei Hu Reported-by: Wenhao Zhang Reported-by: syzbot+e8ce541d095e486074fc@syzkaller.appspotmail.com Reviewed-by: Zhiqiang Liu Acked-by: Martin KaFai Lau Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/ipv6/ip6_output.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 5f9fa0302b5a..e71227390bec 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -595,7 +595,7 @@ int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb, inet6_sk(skb->sk) : NULL; struct ipv6hdr *tmp_hdr; struct frag_hdr *fh; - unsigned int mtu, hlen, left, len; + unsigned int mtu, hlen, left, len, nexthdr_offset; int hroom, troom; __be32 frag_id; int ptr, offset = 0, err = 0; @@ -606,6 +606,7 @@ int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb, goto fail; hlen = err; nexthdr = *prevhdr; + nexthdr_offset = prevhdr - skb_network_header(skb); mtu = ip6_skb_dst_mtu(skb); @@ -640,6 +641,7 @@ int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb, (err = skb_checksum_help(skb))) goto fail; + prevhdr = skb_network_header(skb) + nexthdr_offset; hroom = LL_RESERVED_SPACE(rt->dst.dev); if (skb_has_frag_list(skb)) { unsigned int first_len = skb_pagelen(skb); -- 2.19.1