From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk1-x736.google.com (mail-qk1-x736.google.com [IPv6:2607:f8b0:4864:20::736]) by sourceware.org (Postfix) with ESMTPS id 2BC493854832 for ; Tue, 13 Apr 2021 11:53:26 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 2BC493854832 Received: by mail-qk1-x736.google.com with SMTP id o17so8994505qkl.13 for ; Tue, 13 Apr 2021 04:53:26 -0700 (PDT) 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=tSNu4IyhQvonLe24K5C9cZqEjm0cUNcTJLEzXdR4lmE=; b=FazKjGmamI5YA8EMyHgCQZ6R2L/U/9g9LZoNUgKMvRStimR6yfIcWTwkrwbqmOXHx9 I6OmbvhCr+5taXQnC4CEcCHYxyIp+u7rXZxjAtC7eo0qDm1/hr0/I0rOyYuUXMHpWhnX 2jXxkEI00RT+lXHIuaH3+89J7oUeWPgkjxGUZd+qKt5eb2uXYumBGSLxaT+i7adrjF5P xZ5B7frrxr0eTwX7NKHVW7KpMBHS69qfw06s/QASy03B9EIlHanMGJOIUcGklwQ1ZXVJ tBjtNaPxVszkEes5SZTmMFi+YHHkVJfnXTMLF0a//NHWZYDatDAZy4Rg2wGaT952YH6G CPEA== X-Gm-Message-State: AOAM533x6kRRWrM0tWkolhkfLlm4ANl9L0DNdqs4LYEvtz178/we8jz9 P1Sh+HjIWRu9bfuZHKQDAqAEgF9IZzc1N0xy X-Google-Smtp-Source: ABdhPJzAm0+a7taAfnJTKc5zXpSdqn3yyAH/tVrw0ymz7u5+PGxYS2o54RLrXQVmnk1lA0z7kGyp8g== X-Received: by 2002:a05:620a:13c3:: with SMTP id g3mr19354201qkl.377.1618314805572; Tue, 13 Apr 2021 04:53:25 -0700 (PDT) Received: from [192.168.1.132] ([177.194.41.149]) by smtp.gmail.com with ESMTPSA id z17sm9599859qtf.10.2021.04.13.04.53.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 13 Apr 2021 04:53:25 -0700 (PDT) Subject: Re: [PATCH] linux: sysconf: limit _SC_MAX_ARG to 6 MiB [BZ #25305] To: Michal Nazarewicz , libc-alpha@sourceware.org References: <20210407151058.1176364-1-mina86@mina86.com> <46c3ea60-7a57-14f7-92f9-e915e3b12dae@linaro.org> From: Adhemerval Zanella Message-ID: Date: Tue, 13 Apr 2021 08:53:23 -0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-12.5 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, NICE_REPLY_A, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 13 Apr 2021 11:53:28 -0000 On 12/04/2021 18:31, Michal Nazarewicz wrote: >> On 07/04/2021 12:10, Michal Nazarewicz wrote: >>> Since Linux 4.13, kernel limits the maximum command line arguments >>> length to 6 MiB.¹ Normally the limit is still quarter of the maximum >>> stack size but if that limit exceeds 6 MiB it’s clamped down. > > On Mon, Apr 12 2021, Adhemerval Zanella wrote: >> Patch look good to me, thanks. >> >> Reviewed=by: Adhemerval Zanella >> >>> --- >>> sysdeps/unix/sysv/linux/sysconf.c | 5 ++++- >>> 1 file changed, 4 insertions(+), 1 deletion(-) >>> >>> diff --git a/sysdeps/unix/sysv/linux/sysconf.c b/sysdeps/unix/sysv/linux/sysconf.c >>> index 366fcef01e..bd711795c7 100644 >>> --- a/sysdeps/unix/sysv/linux/sysconf.c >>> +++ b/sysdeps/unix/sysv/linux/sysconf.c >>> @@ -55,7 +55,10 @@ __sysconf (int name) >>> struct rlimit rlimit; >>> /* Use getrlimit to get the stack limit. */ >>> if (__getrlimit (RLIMIT_STACK, &rlimit) == 0) >>> - return MAX (legacy_ARG_MAX, rlimit.rlim_cur / 4); >>> + { >>> + const long int limit = MAX (legacy_ARG_MAX, rlimit.rlim_cur / 4); >>> + return MIN (limit, 6 << 10 << 10); >> >> I think it a bit easier to read with the value expanded (6291456). > > I’d rather go with ‘6 * 1024 * 1024’ if shifts aren’t readable. Alright, I will change it and commit for you.