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=-3.9 required=3.0 tests=BAYES_00,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 4832CC00A89 for ; Fri, 30 Oct 2020 14:30:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D23D822227 for ; Fri, 30 Oct 2020 14:30:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="CPD8K/yw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726760AbgJ3Oaw (ORCPT ); Fri, 30 Oct 2020 10:30:52 -0400 Received: from mx2.suse.de ([195.135.220.15]:47700 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725975AbgJ3Oaw (ORCPT ); Fri, 30 Oct 2020 10:30:52 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1604068250; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=dzYRrHej5hwjdfH+v+jsCGMI1ohR5+BirpcUtCHUXxQ=; b=CPD8K/ywq8vKYtZW5A2+PtWBC4VF2z7PYJKPwv2MMTuvQ66KNaZzlhmyOFkQpOOWU0nGlU hZBN5dX22vj+/LXY62V7n/T1Hs7LKOqWQoBsHBQS99fPgM4Cr6VGBTUFGR4vyih15fy0jp B/p/LKjHKTqkd+hvpDp2gc0ENNGOCaA= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 0117BAE0F; Fri, 30 Oct 2020 14:30:50 +0000 (UTC) Date: Fri, 30 Oct 2020 15:30:49 +0100 From: Petr Mladek To: Matteo Croce Cc: linux-kernel@vger.kernel.org, Guenter Roeck , Arnd Bergmann , Mike Rapoport , Kees Cook , Pavel Tatashin , Robin Holt , Fabian Frederick , stable@vger.kernel.org Subject: Re: [PATCH v2 2/2] reboot: fix parsing of reboot cpu number Message-ID: <20201030143049.GE1602@alley> References: <20201027133545.58625-1-mcroce@linux.microsoft.com> <20201027133545.58625-3-mcroce@linux.microsoft.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201027133545.58625-3-mcroce@linux.microsoft.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 2020-10-27 14:35:45, Matteo Croce wrote: > From: Matteo Croce > > The kernel cmdline reboot= argument allows to specify the CPU used > for rebooting, with the syntax `s####` among the other flags, e.g. > > reboot=soft,s4 > reboot=warm,s31,force > > In the early days the parsing was done with simple_strtoul(), later > deprecated in favor of the safer kstrtoint() which handles overflow. > > But kstrtoint() returns -EINVAL if there are non-digit characters > in a string, so if this flag is not the last given, it's silently > ignored as well as the subsequent ones. > > To fix it, revert the usage of simple_strtoul(), which is no longer > deprecated, and restore the old behaviour. > > While at it, merge two identical code blocks into one. > --- a/kernel/reboot.c > +++ b/kernel/reboot.c > @@ -552,25 +552,19 @@ static int __init reboot_setup(char *str) > > case 's': > { > - int rc; > - > - if (isdigit(*(str+1))) { > - rc = kstrtoint(str+1, 0, &reboot_cpu); > - if (rc) > - return rc; > - if (reboot_cpu >= num_possible_cpus()) { > - reboot_cpu = 0; > - return -ERANGE; > - } > - } else if (str[1] == 'm' && str[2] == 'p' && > - isdigit(*(str+3))) { > - rc = kstrtoint(str+3, 0, &reboot_cpu); > - if (rc) > - return rc; > - if (reboot_cpu >= num_possible_cpus()) { > - reboot_cpu = 0; ^^^^^^ > + int cpu; > + > + /* > + * reboot_cpu is s[mp]#### with #### being the processor > + * to be used for rebooting. Skip 's' or 'smp' prefix. > + */ > + str += str[1] == 'm' && str[2] == 'p' ? 3 : 1; > + > + if (isdigit(str[0])) { > + cpu = simple_strtoul(str, NULL, 0); > + if (cpu >= num_possible_cpus()) > return -ERANGE; > - } > + reboot_cpu = cpu; The original value stays when the new one is out of range. It is small functional change that should get mentioned in the commit message or better fixed separately. Hmm, I suggest to split this into 3 patches and switch the order: + 1st patch should simply revert the commit 616feab75397 ("kernel/reboot.c: convert simple_strtoul to kstrtoint"). + 2nd patch should merge the two branches without any functional change. + 3rd patch should add the check for num_possible_cpus() and update the value only when it is valid. I am sorry that I did not suggested this when reviewed v1. I have missed this functional change at that time. Best Regards, Petr