From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1754663AbbE0TRA (ORCPT <rfc822;w@1wt.eu>);
	Wed, 27 May 2015 15:17:00 -0400
Received: from smtprelay0024.hostedemail.com ([216.40.44.24]:39024 "EHLO
	smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL)
	by vger.kernel.org with ESMTP id S1754637AbbE0TQx (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Wed, 27 May 2015 15:16:53 -0400
X-Session-Marker: 6A6F6540706572636865732E636F6D
X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,joe@perches.com,:::::::::::::::::::::::::::::::,RULES_HIT:41:355:379:541:599:960:968:973:988:989:1260:1277:1311:1313:1314:1345:1359:1373:1437:1515:1516:1518:1534:1541:1593:1594:1711:1730:1747:1777:1792:2110:2393:2553:2559:2562:2828:3138:3139:3140:3141:3142:3167:3353:3622:3865:3867:3868:3870:3872:3874:4250:4321:5007:6142:6143:6261:6742:7903:10004:10400:10848:11026:11232:11473:11657:11658:11914:12043:12296:12438:12517:12519:12555:12740:13069:13138:13231:13311:13357:21080:21088,0,RBL:none,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fn,MSBL:0,DNSBL:none,Custom_rules:0:0:0
X-HE-Tag: trip30_1e5c2cd6c8e41
X-Filterd-Recvd-Size: 2982
Message-ID: <1432754207.2846.162.camel@perches.com>
Subject: Re: [tip:x86/cpu] x86/cpu: Strip any /proc/ cpuinfo model name
 field whitespace
From: Joe Perches <joe@perches.com>
To: Borislav Petkov <bp@alien8.de>
Cc: luto@amacapital.net, peterz@infradead.org, dvlasenk@redhat.com,
        torvalds@linux-foundation.org, imammedo@redhat.com, brgerst@gmail.com,
        mingo@kernel.org, prarit@redhat.com, dave.hansen@linux.intel.com,
        fenghua.yu@intel.com, hpa@zytor.com, linux-kernel@vger.kernel.org,
        tglx@linutronix.de, bp@suse.de, linux-tip-commits@vger.kernel.org
Date: Wed, 27 May 2015 12:16:47 -0700
In-Reply-To: <20150527190626.GC19407@pd.tnic>
References: <1432050210-32036-1-git-send-email-prarit@redhat.com>
	 <1432628901-18044-15-git-send-email-bp@alien8.de>
	 <tip-adafb98da6a7af5e45362933a7dae6ab0e5076bf@git.kernel.org>
	 <1432746454.2846.154.camel@perches.com> <20150527190626.GC19407@pd.tnic>
Content-Type: text/plain; charset="ISO-8859-1"
X-Mailer: Evolution 3.12.11-0ubuntu3 
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Wed, 2015-05-27 at 21:06 +0200, Borislav Petkov wrote:
> On Wed, May 27, 2015 at 10:07:34AM -0700, Joe Perches wrote:
> > This code can memmove from beyond the x86_model_id field.
> 
> ... in the theoretical case where some model ID has more than 64 - 48
> preceding white spaces.
> 
> I guess we want to be prepared here for insane CPU model IDs coming from
> virtualization.
> 
> > Maybe:
> > 	char *model = strim(c->x86_model_id);
> > 	memmove(c->x86_model_id, model, strlen(model) + 1);
> 
> Yes, and additionally limit that string length:
> 
> ---
> diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
[]
> @@ -383,6 +383,9 @@ static const struct cpu_dev *cpu_devs[X86_VENDOR_NUM] = {};
>  static void get_model_name(struct cpuinfo_x86 *c)
>  {
>  	unsigned int *v;
> +	const char *model;
> +
> +#define MODEL_ID_MAXLEN 48
>  
>  	if (c->extended_cpuid_level < 0x80000004)
>  		return;
> @@ -391,13 +394,15 @@ static void get_model_name(struct cpuinfo_x86 *c)
>  	cpuid(0x80000002, &v[0], &v[1], &v[2], &v[3]);
>  	cpuid(0x80000003, &v[4], &v[5], &v[6], &v[7]);
>  	cpuid(0x80000004, &v[8], &v[9], &v[10], &v[11]);
> -	c->x86_model_id[48] = 0;
> +	c->x86_model_id[MODEL_ID_MAXLEN] = 0;
>  
>  	/*
>  	 * Remove leading whitespace on Intel processors and trailing
>  	 * whitespace on AMD processors.
>  	 */
> -	memmove(c->x86_model_id, strim(c->x86_model_id), 48);
> +	model = strim(c->x86_model_id);
> +
> +	memmove(c->x86_model_id, model, strnlen(model, MODEL_ID_MAXLEN) + 1);

I don't see any value in the #define or strnlen over strlen as
it's guaranteed terminated by the = 0 above, but <shrug> thanks.

cheers, Joe