From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753671AbcEBLe5 (ORCPT ); Mon, 2 May 2016 07:34:57 -0400 Received: from mail-lf0-f41.google.com ([209.85.215.41]:33630 "EHLO mail-lf0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753465AbcEBLey convert rfc822-to-8bit (ORCPT ); Mon, 2 May 2016 07:34:54 -0400 MIME-Version: 1.0 In-Reply-To: <1462167374-6321-1-git-send-email-chengang@emindsoft.com.cn> References: <1462167374-6321-1-git-send-email-chengang@emindsoft.com.cn> Date: Mon, 2 May 2016 13:34:52 +0200 Message-ID: Subject: Re: [PATCH] mm/kasan/kasan.h: Fix boolean checking issue for kasan_report_enabled() From: Alexander Potapenko To: Chen Gang Cc: Andrew Morton , Andrey Ryabinin , Dmitriy Vyukov , kasan-dev , LKML , Linux Memory Management List , Chen Gang Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 2, 2016 at 7:36 AM, wrote: > From: Chen Gang > > According to kasan_[dis|en]able_current() comments and the kasan_depth' > s initialization, if kasan_depth is zero, it means disable. The comments for those functions are really poor, but there's nothing there that says kasan_depth==0 disables KASAN. Actually, kasan_report_enabled() is currently the only place that denotes the semantics of kasan_depth, so it couldn't be wrong. init_task.kasan_depth is 1 during bootstrap and is then set to zero by kasan_init() For every other thread, current->kasan_depth is zero-initialized. > So need use "!!kasan_depth" instead of "!kasan_depth" for checking > enable. > > Signed-off-by: Chen Gang > --- > mm/kasan/kasan.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h > index 7da78a6..6464b8f 100644 > --- a/mm/kasan/kasan.h > +++ b/mm/kasan/kasan.h > @@ -102,7 +102,7 @@ static inline const void *kasan_shadow_to_mem(const void *shadow_addr) > > static inline bool kasan_report_enabled(void) > { > - return !current->kasan_depth; > + return !!current->kasan_depth; > } > > void kasan_report(unsigned long addr, size_t size, > -- > 1.9.3 > -- Alexander Potapenko Software Engineer Google Germany GmbH Erika-Mann-Straße, 33 80636 München Geschäftsführer: Matthew Scott Sucherman, Paul Terence Manicle Registergericht und -nummer: Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg