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=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 7C1E6C3A5A2 for ; Tue, 3 Sep 2019 08:17:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5F21622CF8 for ; Tue, 3 Sep 2019 08:17:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728128AbfICIRC (ORCPT ); Tue, 3 Sep 2019 04:17:02 -0400 Received: from relay12.mail.gandi.net ([217.70.178.232]:38859 "EHLO relay12.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726062AbfICIRC (ORCPT ); Tue, 3 Sep 2019 04:17:02 -0400 Received: from localhost (aclermont-ferrand-651-1-259-53.w86-207.abo.wanadoo.fr [86.207.98.53]) (Authenticated sender: alexandre.belloni@bootlin.com) by relay12.mail.gandi.net (Postfix) with ESMTPSA id 25DB920001B; Tue, 3 Sep 2019 08:16:58 +0000 (UTC) Date: Tue, 3 Sep 2019 10:16:58 +0200 From: Alexandre Belloni To: Yizhuo Zhai Cc: Chengyu Song , Zhiyun Qian , Daniel Lezcano , Thomas Gleixner , Nicolas Ferre , Ludovic Desroches , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] clocksource: atmel-st: Variable sr in at91rm9200_timer_interrupt() could be uninitialized Message-ID: <20190903081658.GK21922@piout.net> References: <20190902222946.20548-1-yzhai003@ucr.edu> <20190902223650.GJ21922@piout.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/09/2019 22:56:48-0700, Yizhuo Zhai wrote: > In function regmap_read(), there're two places which could make the read fail. > > First, if "reg" and "map->reg_stride" are not aligned, then remap_read() will > return -EINVAL without initialize variable "val". > A quick look at of_syscon_register would show you that this is not possible. > Second, _regmap_read() could also fail and return error code if "val" is not > initialized. The caller remap_read() returns the same error code, but > at91rm9200_timer_interrupt() does not use this information. > How would _regmap_read fail exactly? > On Mon, Sep 2, 2019 at 3:37 PM Alexandre Belloni > wrote: > > > > On 02/09/2019 15:29:46-0700, Yizhuo wrote: > > > Inside function at91rm9200_timer_interrupt(), variable sr could > > > be uninitialized if regmap_read() fails. However, sr is used > > > > Could you elaborate on how this could fail? > > > > > to decide the control flow later in the if statement, which is > > > potentially unsafe. We could check the return value of > > > regmap_read() and print an error here. > > > > > > Signed-off-by: Yizhuo > > > --- > > > drivers/clocksource/timer-atmel-st.c | 8 +++++++- > > > 1 file changed, 7 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/clocksource/timer-atmel-st.c b/drivers/clocksource/timer-atmel-st.c > > > index ab0aabfae5f0..061a3f27847e 100644 > > > --- a/drivers/clocksource/timer-atmel-st.c > > > +++ b/drivers/clocksource/timer-atmel-st.c > > > @@ -48,8 +48,14 @@ static inline unsigned long read_CRTR(void) > > > static irqreturn_t at91rm9200_timer_interrupt(int irq, void *dev_id) > > > { > > > u32 sr; > > > + int ret; > > > + > > > + ret = regmap_read(regmap_st, AT91_ST_SR, &sr); > > > + if (ret) { > > > + pr_err("Fail to read AT91_ST_SR.\n"); > > > + return ret; > > > + } > > > > > > - regmap_read(regmap_st, AT91_ST_SR, &sr); > > > sr &= irqmask; > > > > > > /* > > > -- > > > 2.17.1 > > > > > > > -- > > Alexandre Belloni, Bootlin > > Embedded Linux and Kernel engineering > > https://bootlin.com > > > > -- > Kind Regards, > > Yizhuo Zhai > > Computer Science, Graduate Student > University of California, Riverside -- Alexandre Belloni, Bootlin Embedded Linux and Kernel engineering https://bootlin.com