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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 DA0A7C433DF for ; Wed, 13 May 2020 16:58:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 43C3320671 for ; Wed, 13 May 2020 16:58:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389800AbgEMQ6x (ORCPT ); Wed, 13 May 2020 12:58:53 -0400 Received: from verein.lst.de ([213.95.11.211]:47611 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727120AbgEMQ6x (ORCPT ); Wed, 13 May 2020 12:58:53 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id A458168B05; Wed, 13 May 2020 18:58:50 +0200 (CEST) Date: Wed, 13 May 2020 18:58:50 +0200 From: Christoph Hellwig To: Eric Dumazet Cc: Christoph Hellwig , "David S. Miller" , Jakub Kicinski , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/3] net: cleanly handle kernel vs user buffers for ->msg_control Message-ID: <20200513165850.GA26121@lst.de> References: <20200511115913.1420836-1-hch@lst.de> <20200511115913.1420836-4-hch@lst.de> <20200513160938.GA22381@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 13, 2020 at 09:18:36AM -0700, Eric Dumazet wrote: > Please try the following syzbot repro, since it crashes after your patch. Doesn't crash here, but I could totally see why it could depending in the stack initialization. Please try the patch below - these msghdr intance were something I missed because they weren't using any highlevel recvmsg interfaces. I'll do another round of audits to see if there is anything else. diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c index 18d05403d3b52..a0e50cc57e545 100644 --- a/net/ipv6/ipv6_sockglue.c +++ b/net/ipv6/ipv6_sockglue.c @@ -1075,6 +1075,7 @@ static int do_ipv6_getsockopt(struct sock *sk, int level, int optname, msg.msg_control = optval; msg.msg_controllen = len; msg.msg_flags = flags; + msg.msg_control_is_user = true; lock_sock(sk); skb = np->pktoptions;