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=-14.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,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 A5F39C43462 for ; Sun, 9 May 2021 22:11:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7309961396 for ; Sun, 9 May 2021 22:11:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229999AbhEIWMT (ORCPT ); Sun, 9 May 2021 18:12:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45448 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229699AbhEIWMS (ORCPT ); Sun, 9 May 2021 18:12:18 -0400 Received: from mail-oi1-x22b.google.com (mail-oi1-x22b.google.com [IPv6:2607:f8b0:4864:20::22b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 63796C061573 for ; Sun, 9 May 2021 15:11:14 -0700 (PDT) Received: by mail-oi1-x22b.google.com with SMTP id c3so14061851oic.8 for ; Sun, 09 May 2021 15:11:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to:content-language:content-transfer-encoding; bh=myQVw89np4+hZbHk+MUQbcs29nedLhEONbPUxMmU6h0=; b=mhWf5PI6B+wGCtmdKX6k3ri5YdAgv4DEn47B89Z3lsXNaTjKQ1XamuSQhT0FoQF+mG 31CgVJe89MZDs0E02eWYrtO9iBlYKnpeh/YVT+C19nR2I1UhFSjMo0LBvGcjeVbRDcj+ KKlOzB/km24BOohPUXWTGjbi/nem9tiv29gRND7z/vA0azmKtJ5cl91z6gt2GZfdp1Ko C55X7ZXZUrfWGA+ZB5v2FWG1pnsJYVIYRbx7SvWdYMaNL6k4A83+JHVg8NryDvoQdSeX MdxG2xf1kyIKroOuQbSj+KEspdC53/KluK33g+rxEvfx8dDoxMnR4Tl5LNGnnfOj2/7s 0WMw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=myQVw89np4+hZbHk+MUQbcs29nedLhEONbPUxMmU6h0=; b=Rjx+95qfcZzf9ebxArIHGX39Xb9RVoDScr+pMz6QBMX3BZ9vWyWZvA70Z/LLaLHAYI xTndf684OYhBCVp04CtWH+O/8z+4sOjHRimFcPaRD6uYACHxjSs1NgfZ1rBgjPIRxb5Y Ae7RtpSMGsvmqoTP0KvTnM6nS2fLFov5HjfsrNNst/pk4QP6TGHILlk6pAnIEZD4vPLf 9v6bUNm98VzUeT8fXFuMt5Km5IHguwbsN9jyGTQXGYli6E1oYgnW41yZ931UggB8gS6y nRsgNtpsFuwoy6/zYLjco7BqBIAVrPoyXz18UcLT5vR+63K36wihU/wDgMODMZ772Mnq JzlQ== X-Gm-Message-State: AOAM531GPJJXdHua+rP9amiEIRy927DAouV+MQNQheZAi5zDdrqQnKQ2 7Ed95VSHP6l87Yi19j7/HNX/57EKIIs= X-Google-Smtp-Source: ABdhPJxljzoDMSOoJtkwI0bCsccsBUc7tfCGfFCmD3+WGQSJaTGT0Fp5d3bQKtn3DEQnHGPYLbRSFA== X-Received: by 2002:aca:4f4a:: with SMTP id d71mr7550893oib.128.1620598273790; Sun, 09 May 2021 15:11:13 -0700 (PDT) Received: from Davids-MacBook-Pro.local ([2601:282:800:dc80:5d79:6512:fce6:88aa]) by smtp.googlemail.com with ESMTPSA id w10sm2315345oou.35.2021.05.09.15.11.13 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 09 May 2021 15:11:13 -0700 (PDT) Subject: Re: [PATCH iproute2] mptcp: avoid uninitialised errno usage To: Florian Westphal , netdev@vger.kernel.org References: <20210503103631.30694-1-fw@strlen.de> From: David Ahern Message-ID: Date: Sun, 9 May 2021 16:11:11 -0600 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <20210503103631.30694-1-fw@strlen.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 5/3/21 4:36 AM, Florian Westphal wrote: > The function called *might* set errno based on errno value in NLMSG_ERROR > message, but in case no such message exists errno is left alone. > > This may cause ip to fail with > "can't subscribe to mptcp events: Success" > > on kernels that support mptcp but lack event support (all kernels <= 5.11). > > Set errno to a meaningful value. This will then still exit with the > more specific 'permission denied' or some such when called by process > that lacks CAP_NET_ADMIN on 5.12 and later. > > Fixes: ff619e4fd370 ("mptcp: add support for event monitoring") > Signed-off-by: Florian Westphal > --- > ip/ipmptcp.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/ip/ipmptcp.c b/ip/ipmptcp.c > index 5f490f0026d9..504b5b2f5329 100644 > --- a/ip/ipmptcp.c > +++ b/ip/ipmptcp.c > @@ -491,6 +491,9 @@ out: > > static int mptcp_monitor(void) > { > + /* genl_add_mcast_grp may or may not set errno */ > + errno = EOPNOTSUPP; > + > if (genl_add_mcast_grp(&genl_rth, genl_family, MPTCP_PM_EV_GRP_NAME) < 0) { > perror("can't subscribe to mptcp events"); > return 1; > Seems like this should be set in genl_add_mcast_grp vs its caller.