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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 807B7C433F5 for ; Sat, 18 Sep 2021 08:33:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6030061244 for ; Sat, 18 Sep 2021 08:33:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237810AbhIRIef (ORCPT ); Sat, 18 Sep 2021 04:34:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51516 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237529AbhIRIee (ORCPT ); Sat, 18 Sep 2021 04:34:34 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 55D15C061574 for ; Sat, 18 Sep 2021 01:33:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=qP8I4c5RZ5eqoGth3x9+VH7S8unuyvZuAzXJKL9Y7rE=; b=PC1L2AF3OuZHF6NdpfAkcKWOY4 1ONr0nc57MJjuS9UfT8LfjCeacPITBWAlqYYk+6gTG2t8l1L2yyhh/m1+YG9j13HR6bqYed4QDc/D blc3f0keGJ2BaHgWFEq21hz1/26s90vg1IXtUEGXWexJkafGftA+uH8v0sW02YGPshwBv0JXoIRiI 4lAaowECbvksSoS2oTedvgtVnvYlEI3HS8/EVygQYt9dUZPZj7TVc5GzR4qV2rgDzAFJhTPQ+bziP 4T4xZDBlExVTl0Qa8vz4wjA0ZYswwd1GbOatWl2hGQ++chbVukJ3gX8dSPKrcutL2inC/6FYIeU7l NgUV/Yag==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=worktop.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mRVkn-000zzj-1u; Sat, 18 Sep 2021 08:31:32 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id 91B0F986249; Sat, 18 Sep 2021 10:31:20 +0200 (CEST) Date: Sat, 18 Sep 2021 10:31:20 +0200 From: Peter Zijlstra To: cgel.zte@gmail.com Cc: dave.hansen@linux.intel.com, luto@kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, jan.kiszka@siemens.com, jmoyer@redhat.com, dan.j.williams@intel.com, neilb@suse.de, yang.guang5@zte.com.cn, linux-kernel@vger.kernel.org, Greg Kroah-Hartman Subject: Re: [PATCH] Modify the check condition Message-ID: <20210918083120.GM4323@worktop.programming.kicks-ass.net> References: <20210918065232.239336-1-yang.guang5@zte.com.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210918065232.239336-1-yang.guang5@zte.com.cn> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Sep 18, 2021 at 06:52:32AM +0000, cgel.zte@gmail.com wrote: > From: Yang Guang > > The vma may be NULL, and accessing the member of vma like "vma->vm_start" > in calling follow_phys may occur segmentation fault. > So it should check vma at beginning. If vma is null, it will return. And > the if condition won't execute "vm->vm_flags". > > Signed-off-by: Yang Guang > --- > arch/x86/mm/pat/memtype.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/mm/pat/memtype.c b/arch/x86/mm/pat/memtype.c > index 4ba2a3ee4bce..b7108b37b754 100644 > --- a/arch/x86/mm/pat/memtype.c > +++ b/arch/x86/mm/pat/memtype.c > @@ -1089,7 +1089,7 @@ void untrack_pfn(struct vm_area_struct *vma, unsigned long pfn, > resource_size_t paddr; > unsigned long prot; > > - if (vma && !(vma->vm_flags & VM_PAT)) > + if (!(vma) || !(vma->vm_flags & VM_PAT)) > return; Yet another braindead patch that shows you don't actually understand C.