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=-2.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_NEOMUTT 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 6DA70C7112A for ; Sun, 14 Oct 2018 18:53:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 24D962077C for ; Sun, 14 Oct 2018 18:53:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=brauner.io header.i=@brauner.io header.b="L747lWAW" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 24D962077C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=brauner.io Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726593AbeJOCfw (ORCPT ); Sun, 14 Oct 2018 22:35:52 -0400 Received: from mail-wr1-f66.google.com ([209.85.221.66]:36950 "EHLO mail-wr1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726299AbeJOCfw (ORCPT ); Sun, 14 Oct 2018 22:35:52 -0400 Received: by mail-wr1-f66.google.com with SMTP id y11-v6so18727379wrd.4 for ; Sun, 14 Oct 2018 11:53:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=brauner.io; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=JuhbEV0U6hwhoL05wMR+1rOAMqMihGmwHMLvhRaHFR4=; b=L747lWAWt3gdH0jlbv/1R4fMLbdzuBMOPUGHVZUZEbCaKhqly5zsI7tOSrn6V/I6HG kNEwNiRMOKdvso0w1jdU86dWuh80pSvP/MGzJ/fMUBq5wwkx4zBNgn8UAEETsq6IfJ2U LLldL6xrdHRSzQo6/KBevzgCY5PWkQkhideRB7u/KQtctLwB90igQUfBpy1JxEQsUIx5 Anu1sSsyzKik/y7+vmak0QG/fSIORBChYCTzVctZlRCNV3XSTrslwA3jRx95xuj8O1TO FEbAG9augUq8ZBbXJlMzkpNlLwD+XdiEdG0t9SI+r6URATqYpM3EMFjXdB07NogCfkc7 FMIQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=JuhbEV0U6hwhoL05wMR+1rOAMqMihGmwHMLvhRaHFR4=; b=YBiYhyoaVq76Dmo08LcH3BcRHgYWflqZ8HPMOYPzTNSUIN6+HW7jeSchBB2sy6pxnN 7tvCEkMc4Uywfmua8DywolLv7rf8SHod+aI57Ni0tq6iCn8gxOvVcqztP/J/idC/KVPP hnT8nUFMOGSSOjA4wTw0X4QvbBfFdvF6yguOZ8+rozCKX6dMcrEhU2hnir7p1QzFImqK jIzwP5kxCSCSuJR73kkrMX4iSvNhaN4cpzmc8yPn0YYso0VBGiDc/6EIqZxnTdDc/FrD vajbNGfknCOCVAdS0Mmr8AZlHzFdsYoJ6BZt66P8IOmJAEgZaqoYuY+z0PDX+x7yr7ly UG2g== X-Gm-Message-State: ABuFfoijXP2dC4E5CwTTRMbvXOkiyiy2og6QB4a4nY25gLNvCNLnB5xk noVy1o62Xo70TKolMo7lVVbAHQ== X-Google-Smtp-Source: ACcGV62FJsx9c+UyYU0Ab+bXleNjCO+VI7UpRPEAHtq8yM0kk8o8VkoMi5TkjG0Ph0XTJHTQxN8RDg== X-Received: by 2002:adf:be07:: with SMTP id n7-v6mr11328224wrh.267.1539543233485; Sun, 14 Oct 2018 11:53:53 -0700 (PDT) Received: from brauner.io ([2a02:8070:8895:9700:8197:8849:535a:4f00]) by smtp.gmail.com with ESMTPSA id e67-v6sm7074463wmd.41.2018.10.14.11.53.52 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Sun, 14 Oct 2018 11:53:52 -0700 (PDT) Date: Sun, 14 Oct 2018 20:53:46 +0200 From: Christian Brauner To: Al Viro Cc: keescook@chromium.org, linux-kernel@vger.kernel.org, ebiederm@xmission.com, mcgrof@kernel.org, akpm@linux-foundation.org, joe.lawrence@redhat.com, longman@redhat.com Subject: Re: [PATCH 1/2] sysctl: add overflow detection to proc_get_long() Message-ID: <20181014185345.o6uokigiytqugg6v@brauner.io> References: <20181014132510.25943-1-christian@brauner.io> <20181014132510.25943-2-christian@brauner.io> <20181014171855.GW32577@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20181014171855.GW32577@ZenIV.linux.org.uk> User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Oct 14, 2018 at 06:18:55PM +0100, Al Viro wrote: > On Sun, Oct 14, 2018 at 03:25:09PM +0200, Christian Brauner wrote: > > > +static unsigned long sysctl_strtoul_lenient(const char *cp, char **endp, > > + unsigned int base, bool *overflow) > > +{ > > + unsigned long long result; > > + unsigned int rv; > > + > > + cp = _parse_integer_fixup_radix(cp, &base); > > + rv = _parse_integer(cp, base, &result); > > + if ((rv & KSTRTOX_OVERFLOW) || > > + (result != (unsigned long long)(unsigned long)result)) > > + *overflow = true; > > + else > > + *overflow = false; > > Yecchh... First of all, the cast back to unsigned long long is completely > pointless. What's more, Sorry, seriously asking: why? This was meant to handle the case where sizeof(unsigned long long) != sizeof(unsigned long) and I just looked at _kstrtoul() which does the same: int _kstrtoul(const char *s, unsigned int base, unsigned long *res) { unsigned long long tmp; int rv; rv = kstrtoull(s, base, &tmp); if (rv < 0) return rv; if (tmp != (unsigned long long)(unsigned long)tmp) return -ERANGE; *res = tmp; return 0; } Sorry, if I'm being dense here. > if (expr) > foo = true; > else > foo = flase; > is a fairly unidiomatic way to spell foo = expr; > > And... is there anything that would really care if this "overflow" thing had > been replaced by simply returning ~0UL on such? That would appear to be > a lot more natural API... Yes, I thought about this but I really didn't want to risk breaking anything that relies on the weird old behavior. We can change it to that and assume that anything that doesn't explicitly set a maximum value wants to be capped at ULONG_MAX. Fine with me.