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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 BB7EDC2F3D5 for ; Mon, 21 Jan 2019 14:18:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8AB3E20861 for ; Mon, 21 Jan 2019 14:18:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548080324; bh=glmkLuowO4r7MilHL/ar7HO/aQye/g1hqeylnZ401zM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Sp5W9yki6S7l5yOkLmYQJE6hNflrNsU06XpOmcRBwPmnRKf/XHu+qwtKixLrcQJvn Q1doN0jk6MXTLk4bQT4XOdM1DpMj9TP2+jD05CPaqmqRqaAiVviuWgAUrVc42XOMJE OqyutdEdU/meNM9TmSGSK6ZP8sewrOzjowZCBEDg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728926AbfAUOSi (ORCPT ); Mon, 21 Jan 2019 09:18:38 -0500 Received: from mail.kernel.org ([198.145.29.99]:60060 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730235AbfAUNt2 (ORCPT ); Mon, 21 Jan 2019 08:49:28 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.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 57B192087F; Mon, 21 Jan 2019 13:49:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548078566; bh=glmkLuowO4r7MilHL/ar7HO/aQye/g1hqeylnZ401zM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sy/JxgmlacMuDxBxEpWL/BI5qlOIYk0NgHRpcIoouyBpzWBukDCfzns5uh/m6IG9D yas2Pt5os9+LQJ8DoWWJz2PlSKu1y0IR/LuP35lbA2zWN75F0VczKxkf/vomQJs0KT xi5H43qBNATe37SoLTK0VNoUbB0HHo8W27ZJ9Ktc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , Piotr Sawicki , Casey Schaufler , syzbot , "David S. Miller" Subject: [PATCH 4.20 076/111] ipv6: make icmp6_send() robust against null skb->dev Date: Mon, 21 Jan 2019 14:43:10 +0100 Message-Id: <20190121122504.802512921@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190121122455.819406896@linuxfoundation.org> References: <20190121122455.819406896@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 4.20-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet commit 8d933670452107e41165bea70a30dffbd281bef1 upstream. syzbot was able to crash one host with the following stack trace : kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 8625 Comm: syz-executor4 Not tainted 4.20.0+ #8 RIP: 0010:dev_net include/linux/netdevice.h:2169 [inline] RIP: 0010:icmp6_send+0x116/0x2d30 net/ipv6/icmp.c:426 icmpv6_send smack_socket_sock_rcv_skb security_sock_rcv_skb sk_filter_trim_cap __sk_receive_skb dccp_v6_do_rcv release_sock This is because a RX packet found socket owned by user and was stored into socket backlog. Before leaving RCU protected section, skb->dev was cleared in __sk_receive_skb(). When socket backlog was finally handled at release_sock() time, skb was fed to smack_socket_sock_rcv_skb() then icmp6_send() We could fix the bug in smack_socket_sock_rcv_skb(), or simply make icmp6_send() more robust against such possibility. In the future we might provide to icmp6_send() the net pointer instead of infering it. Fixes: d66a8acbda92 ("Smack: Inform peer that IPv6 traffic has been blocked") Signed-off-by: Eric Dumazet Cc: Piotr Sawicki Cc: Casey Schaufler Reported-by: syzbot Acked-by: Casey Schaufler Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv6/icmp.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/net/ipv6/icmp.c +++ b/net/ipv6/icmp.c @@ -421,10 +421,10 @@ static int icmp6_iif(const struct sk_buf static void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info, const struct in6_addr *force_saddr) { - struct net *net = dev_net(skb->dev); struct inet6_dev *idev = NULL; struct ipv6hdr *hdr = ipv6_hdr(skb); struct sock *sk; + struct net *net; struct ipv6_pinfo *np; const struct in6_addr *saddr = NULL; struct dst_entry *dst; @@ -435,12 +435,16 @@ static void icmp6_send(struct sk_buff *s int iif = 0; int addr_type = 0; int len; - u32 mark = IP6_REPLY_MARK(net, skb->mark); + u32 mark; if ((u8 *)hdr < skb->head || (skb_network_header(skb) + sizeof(*hdr)) > skb_tail_pointer(skb)) return; + if (!skb->dev) + return; + net = dev_net(skb->dev); + mark = IP6_REPLY_MARK(net, skb->mark); /* * Make sure we respect the rules * i.e. RFC 1885 2.4(e)