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=-4.5 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 D7E9FC07E99 for ; Thu, 8 Jul 2021 12:26:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B6BD361396 for ; Thu, 8 Jul 2021 12:26:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231152AbhGHM30 (ORCPT ); Thu, 8 Jul 2021 08:29:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49620 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229659AbhGHM3Z (ORCPT ); Thu, 8 Jul 2021 08:29:25 -0400 Received: from mail-wm1-x329.google.com (mail-wm1-x329.google.com [IPv6:2a00:1450:4864:20::329]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BFFC1C061574; Thu, 8 Jul 2021 05:26:42 -0700 (PDT) Received: by mail-wm1-x329.google.com with SMTP id b14-20020a1c1b0e0000b02901fc3a62af78so6567666wmb.3; Thu, 08 Jul 2021 05:26:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=2BNe9rKXhY8MmWQX67o+G5gKAgLO+47b5LDxS9l4Meo=; b=olyx2nDd+kC70burfasIdtGB3O5hE3fqw3l3Tg1BcdWGpI9BUvAtoUbHTyhixSBrDa AHRa6CVMvdm+ROYzQeDNeLYkhb56HPeQ2tIS++yJ09jLKmJ+flmSbe7mEQnltNhX5MdR rlv+/L0RUYPRYX9zJVHvW0Iv/GHXqCqwwFNNyEOnVLjDo+dK2vajysrfs6cTlJy52fhv B0aKfjBKwtPtt5O1fMqDB/Z94RciRu7xqrHvMS3YzVtF266lmppQbGNZ9x/ZQHSPE87X H7Of6CkYFdKyHoDwxLdCkrHSvt6Dq0Q1XvLmp993Ynb5QBAgnKMpIp5mSf/iyTsSGG9f jzQg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=2BNe9rKXhY8MmWQX67o+G5gKAgLO+47b5LDxS9l4Meo=; b=PHOa6KwMK8WcoJZFz8+Ieg5XMl1FSCGg3hIm1sgE0xQwv2+/S0NeO92xfaNtnoz6gU MjcZCtlpFaeMbFsaJVN/YBs0RHvkF9wQasyia9UWTIOlN/wv41q/o0CCr3IGd6JbWMR/ RgiKSkTI3TONBaVKIIMqzh9+nrn7YGXfSu4cOfNOGkjnirPUuRIV/vyLyeL9oeCFdds3 cFoADrLnmZuC6023dpaL0EBzaTU1/PidfZVlzlyYEqOIIfdw6vJLm5cG4iIJz4tHgisx Oq716bZ02TUfULcjTe1SqmUcjyuSoQIAStHKHe2G8YQk2sxZazKIchL253BS1bPkelUi VSPg== X-Gm-Message-State: AOAM530xbdIq5sRQ+hAWCRI9frRP7IGGU9/PCUweLCRPDgYaX/h8ozVW YDIMcRnIeJMN8Sl84lu6FjKG18IHsTg= X-Google-Smtp-Source: ABdhPJwqC/SZxrVdpL1dHpgkIsCDB6Ln1sdmIBorf2K9D6i2ebpS/Hh2T8uSDkVEftaMB12GuV2Yug== X-Received: by 2002:a05:600c:224a:: with SMTP id a10mr5073252wmm.7.1625747201217; Thu, 08 Jul 2021 05:26:41 -0700 (PDT) Received: from [10.0.0.3] ([37.165.6.154]) by smtp.gmail.com with ESMTPSA id s1sm9105516wmj.8.2021.07.08.05.26.38 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 08 Jul 2021 05:26:40 -0700 (PDT) Subject: Re: [PATCH v2] net: rtnetlink: Fix rtnl_dereference may be return NULL To: Vladimir Oltean , Johannes Berg Cc: Yajun Deng , "davem@davemloft.net" , "kuba@kernel.org" , "ryazanov.s.a@gmail.com" , "avagin@gmail.com" , "cong.wang@bytedance.com" , "roopa@cumulusnetworks.com" , "zhudi21@huawei.com" , "edumazet@google.com" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" References: <20210708092936.20044-1-yajun.deng@linux.dev> <3c160d187382677abe40606a6a88ddac0809c328.camel@sipsolutions.net> <20210708111118.kti4jprkz7bus62g@skbuf> From: Eric Dumazet Message-ID: <7e11f410-9a97-c7d8-ee6a-fa776a4d1f0e@gmail.com> Date: Thu, 8 Jul 2021 14:26:37 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210708111118.kti4jprkz7bus62g@skbuf> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/8/21 1:11 PM, Vladimir Oltean wrote: > On Thu, Jul 08, 2021 at 11:43:20AM +0200, Johannes Berg wrote: >> On Thu, 2021-07-08 at 17:29 +0800, Yajun Deng wrote: >>> The value 'link' may be NULL in rtnl_unregister(), this leads to >>> kfree_rcu(NULL, xxx), so add this case handling. >>> >> >> I don't see how. It would require the caller to unregister something >> they never registered. That would be a bug there, but I don't see that >> it's very useful to actually be defensive about bugs there. > > Besides, isn't kfree_rcu(NULL) safe anyway? > Only from linux-5.3 I think. (commit 12edff045bc6dd3ab1565cc02fa4841803c2a633 was not backported to old kernels) But yes, this patch is not solving any bug, as I suspected.