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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 68C83C3F68F for ; Tue, 14 Jan 2020 16:04:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4023224658 for ; Tue, 14 Jan 2020 16:04:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=cloudflare.com header.i=@cloudflare.com header.b="deg2iFB6" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729050AbgANQEh (ORCPT ); Tue, 14 Jan 2020 11:04:37 -0500 Received: from mail-lj1-f194.google.com ([209.85.208.194]:42008 "EHLO mail-lj1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728929AbgANQEh (ORCPT ); Tue, 14 Jan 2020 11:04:37 -0500 Received: by mail-lj1-f194.google.com with SMTP id y4so14957599ljj.9 for ; Tue, 14 Jan 2020 08:04:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; h=references:user-agent:from:to:cc:subject:in-reply-to:date :message-id:mime-version; bh=+H+H6Ga+4JFtfT6TfTdJtyZwGfO1XdaI77oQLwOJulY=; b=deg2iFB69XUcAU6WSbn2FDLcD4JbNZC8FeTdY1N7SHc8F/It16Ab+J8641ymR9dFw8 EIO+oDjPtirFwV+5vC7Qb2ywRg44+k0Rb08OBS6hQwYo0w/97u9nUeU2lSrH1qD69rU3 wP5vAZ7XLShcQpOz5D51mSzfo474ecm9BTSKs= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:references:user-agent:from:to:cc:subject :in-reply-to:date:message-id:mime-version; bh=+H+H6Ga+4JFtfT6TfTdJtyZwGfO1XdaI77oQLwOJulY=; b=J1HBg3eKbxrceWb7E4cqWlLhcP98qkAkXsxGQAjr3fA74/WqqHRic4rpOtWRNEEk1I VyvNkfira1m2/sltMBWG0QPyUobwIz2T0TLBGPeU/N6PB2snPFZbgsF4MMsZjhyHcXvv epN1MEy1bOlAvbU1Qe/zpOjBv82TA/5rkHVBAVJCe1fzC+RZ5p2oOWIrNiJk/iEAP2FU 5juRWvkNuQRh55phwgXs24zvYNvxw2iRXZHMKCyhBRHhP7fuKphabiBuYz48dzqpBu16 3msWgPI/sn7GuuGm5YoF90Y8oJ9R3NZLKEEoxPdJ8o/vdbE1MmjcKHY38jpO5+e0uCXY E6fQ== X-Gm-Message-State: APjAAAXR2i+MlI94y/OmYv+/lu4eJduX5tRYpHiQ+Jgt9eHxnOb3UCDR X6SuiE4BNxCeHolSRZ/aG/bF7w== X-Google-Smtp-Source: APXvYqwD4F55xjnZNU6JSUcx2EG/xlvr4BzRiJ6a4V/9cTyEHEcnLJSGmOGvKH7l4QK52zzwWGd4Nw== X-Received: by 2002:a2e:9510:: with SMTP id f16mr14642612ljh.249.1579017875217; Tue, 14 Jan 2020 08:04:35 -0800 (PST) Received: from cloudflare.com ([176.221.114.230]) by smtp.gmail.com with ESMTPSA id t27sm7827251ljd.26.2020.01.14.08.04.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Jan 2020 08:04:34 -0800 (PST) References: <20200110105027.257877-1-jakub@cloudflare.com> <20200110105027.257877-4-jakub@cloudflare.com> <20200113201456.t5apbcjdqdr6by5t@kafai-mbp.dhcp.thefacebook.com> User-agent: mu4e 1.1.0; emacs 26.3 From: Jakub Sitnicki To: Martin Lau Cc: "bpf\@vger.kernel.org" , "netdev\@vger.kernel.org" , "kernel-team\@cloudflare.com" , Eric Dumazet , "John Fastabend" , Lorenz Bauer Subject: Re: [PATCH bpf-next v2 03/11] net, sk_msg: Clear sk_user_data pointer on clone if tagged In-reply-to: <20200113201456.t5apbcjdqdr6by5t@kafai-mbp.dhcp.thefacebook.com> Date: Tue, 14 Jan 2020 17:04:33 +0100 Message-ID: <87a76qrpm6.fsf@cloudflare.com> MIME-Version: 1.0 Content-Type: text/plain Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, Jan 13, 2020 at 09:15 PM CET, Martin Lau wrote: > On Fri, Jan 10, 2020 at 11:50:19AM +0100, Jakub Sitnicki wrote: >> sk_user_data can hold a pointer to an object that is not intended to be >> shared between the parent socket and the child that gets a pointer copy on >> clone. This is the case when sk_user_data points at reference-counted >> object, like struct sk_psock. >> >> One way to resolve it is to tag the pointer with a no-copy flag by >> repurposing its lowest bit. Based on the bit-flag value we clear the child >> sk_user_data pointer after cloning the parent socket. > LGTM. One nit, WARN_ON_ONCE should be enough for all the cases if they > would ever happen. Having continuous splat on the same thing is not > necessary useful while it could be quite distributing for people > capture/log them. Will switch to WARN_ON_ONCE in v3. Thanks for the review! > > Acked-by: Martin KaFai Lau