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=-8.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 17212C43331 for ; Sun, 10 Nov 2019 18:18:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DA37120842 for ; Sun, 10 Nov 2019 18:18:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573409920; bh=NUjOCkuG6s+MO4FrRDCYkQ+eHMNeT2BDZrcgnAiwmxg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=hSbfirDkkcUpae8EmHWn83vx0McT6DcxO9shCL96M+D0f1DY4t6EFrCxdjnF+RP// oJBEPxYfC5Wo38yMUJkAJjoqPlZTqvKCJKnElAJvd6HVJhRkow1OWwyeT3pkY2KYOe sVljUhF9Ki+veF2rvu1i+z+SKprnFmxkIvOQYrUo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727011AbfKJSSi (ORCPT ); Sun, 10 Nov 2019 13:18:38 -0500 Received: from mail.kernel.org ([198.145.29.99]:42462 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726684AbfKJSSi (ORCPT ); Sun, 10 Nov 2019 13:18:38 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D4EBA20818; Sun, 10 Nov 2019 18:18:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573409916; bh=NUjOCkuG6s+MO4FrRDCYkQ+eHMNeT2BDZrcgnAiwmxg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=NAHgbwyEKyinD2nPXs6VehJUiWWdj5AHc06EAml+gLtqWha0YeNBNCz9SubjMFxw8 n1urBw6M/vDe590m13nAN1CdKh/LrG0TzT5zaaN44ScNaLCfITrTYB1oH+GQytO1/A +E9oHL21XvsfZtW59RsHKO1h8EYHzV5j3AG30MO8= Date: Sun, 10 Nov 2019 19:18:33 +0100 From: Greg KH To: Zheng Yongjun Cc: keescook@chromium.org, arnd@arndb.de, linux-kernel@vger.kernel.org, Hulk Robot Subject: Re: [PATCH] lkdtm: Remove set but not used variable 'byte' Message-ID: <20191110181833.GA3088811@kroah.com> References: <20191110092249.182210-1-zhengyongjun3@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191110092249.182210-1-zhengyongjun3@huawei.com> User-Agent: Mutt/1.12.2 (2019-09-21) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Nov 10, 2019 at 05:22:49PM +0800, Zheng Yongjun wrote: > Fixes gcc '-Wunused-but-set-variable' warning: > > drivers/misc/lkdtm/bugs.c: In function lkdtm_STACK_GUARD_PAGE_LEADING: > drivers/misc/lkdtm/bugs.c:236:25: warning: variable byte set but not used [-Wunused-but-set-variable] > drivers/misc/lkdtm/bugs.c: In function lkdtm_STACK_GUARD_PAGE_TRAILING: > drivers/misc/lkdtm/bugs.c:250:25: warning: variable byte set but not used [-Wunused-but-set-variable] > > byte is never used, so remove it. > > Reported-by: Hulk Robot > Signed-off-by: Zheng Yongjun > --- > drivers/misc/lkdtm/bugs.c | 6 ------ > 1 file changed, 6 deletions(-) > > diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c > index 7284a22b1a09..fcd943725b66 100644 > --- a/drivers/misc/lkdtm/bugs.c > +++ b/drivers/misc/lkdtm/bugs.c > @@ -249,12 +249,9 @@ void lkdtm_STACK_GUARD_PAGE_LEADING(void) > { > const unsigned char *stack = task_stack_page(current); > const unsigned char *ptr = stack - 1; > - volatile unsigned char byte; > > pr_info("attempting bad read from page below current stack\n"); > > - byte = *ptr; > - You do realize just what this code is trying to do _is_ a bug, so it's ok to leave it, right? You just broke the code here with your change as you are trying to "fix" it :) thanks, greg k-h