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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 6E0BBC282CB for ; Tue, 5 Feb 2019 21:59:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 435A720823 for ; Tue, 5 Feb 2019 21:59:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727347AbfBEV7y (ORCPT ); Tue, 5 Feb 2019 16:59:54 -0500 Received: from relay1-d.mail.gandi.net ([217.70.183.193]:39857 "EHLO relay1-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725921AbfBEV7y (ORCPT ); Tue, 5 Feb 2019 16:59:54 -0500 X-Originating-IP: 86.202.150.119 Received: from localhost (lfbn-lyo-1-59-119.w86-202.abo.wanadoo.fr [86.202.150.119]) (Authenticated sender: alexandre.belloni@bootlin.com) by relay1-d.mail.gandi.net (Postfix) with ESMTPSA id 636C0240004; Tue, 5 Feb 2019 21:59:48 +0000 (UTC) Date: Tue, 5 Feb 2019 22:59:39 +0100 From: Alexandre Belloni To: Colin King Cc: Alessandro Zummo , linux-rtc@vger.kernel.org, kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] rtc: rtc-ds1672: fix unintended sign extension Message-ID: <20190205215939.GJ24598@piout.net> References: <20190205180449.28749-1-colin.king@canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190205180449.28749-1-colin.king@canonical.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-rtc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rtc@vger.kernel.org On 05/02/2019 18:04:49+0000, Colin King wrote: > From: Colin Ian King > > Shifting a u8 by 24 will cause the value to be promoted to an integer. If > the top bit of the u8 is set then the following conversion to an unsigned > long will sign extend the value causing the upper 32 bits to be set in > the result. > > Fix this by casting the u8 value to an unsigned long before the shift. > > Detected by CoverityScan, CID#138801 ("Unintended sign extension") > > Fixes: edf1aaa31fc5 ("[PATCH] RTC subsystem: DS1672 driver") > Signed-off-by: Colin Ian King > --- > drivers/rtc/rtc-ds1672.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > Applied, thanks. -- Alexandre Belloni, Bootlin Embedded Linux and Kernel engineering https://bootlin.com