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=-13.5 required=3.0 tests=BAYES_00,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_GIT 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 DBE94C4727C for ; Tue, 29 Sep 2020 11:10:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 996F6216C4 for ; Tue, 29 Sep 2020 11:10:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601377856; bh=8o9zybgIuHAYYolfy9YI06KREygAviigU0xC/9gLius=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=nGmIPrPlAISNFDU2WcYrZ5bnJJOm5+s4Cal0yRzN5HCLowiCJ7+gKMRZYA3c/KrG6 xI+BYrRc/YJPHYoZyD08kcAgajh+aOVezrHxrsJRY3KIVCnNZ0F7RAoS+QyOInmeFS Z6VNb3MMWUuj65uOkdmKCthH5YEoFO0OeFveovpQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728774AbgI2LKr (ORCPT ); Tue, 29 Sep 2020 07:10:47 -0400 Received: from mail.kernel.org ([198.145.29.99]:51292 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728440AbgI2LK2 (ORCPT ); Tue, 29 Sep 2020 07:10:28 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (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 094AF21941; Tue, 29 Sep 2020 11:10:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601377827; bh=8o9zybgIuHAYYolfy9YI06KREygAviigU0xC/9gLius=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zKwkPV4VhsmCuVDmxohZx7+5HVDNoBH0wu8zkZyK95hyyCfKidr7tFdoSM3tQYPSB AL6j9u7r735bIGQompMqOaVv8jf3z7/cgzk7aq9b6X1ZrOMy9cpLPtWT4GhunUlPIo /HP8lPSv+7nerk6OJZOHJ+B1PbacwdNuH6uUzoRc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Wen Yang , Thomas Gleixner , Sasha Levin Subject: [PATCH 4.9 057/121] timekeeping: Prevent 32bit truncation in scale64_check_overflow() Date: Tue, 29 Sep 2020 13:00:01 +0200 Message-Id: <20200929105933.005798011@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200929105930.172747117@linuxfoundation.org> References: <20200929105930.172747117@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Wen Yang [ Upstream commit 4cbbc3a0eeed675449b1a4d080008927121f3da3 ] While unlikely the divisor in scale64_check_overflow() could be >= 32bit in scale64_check_overflow(). do_div() truncates the divisor to 32bit at least on 32bit platforms. Use div64_u64() instead to avoid the truncation to 32-bit. [ tglx: Massaged changelog ] Signed-off-by: Wen Yang Signed-off-by: Thomas Gleixner Link: https://lkml.kernel.org/r/20200120100523.45656-1-wenyang@linux.alibaba.com Signed-off-by: Sasha Levin --- kernel/time/timekeeping.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index e24e1f0c56906..e21b4d8b72405 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -950,9 +950,8 @@ static int scale64_check_overflow(u64 mult, u64 div, u64 *base) ((int)sizeof(u64)*8 - fls64(mult) < fls64(rem))) return -EOVERFLOW; tmp *= mult; - rem *= mult; - do_div(rem, div); + rem = div64_u64(rem * mult, div); *base = tmp + rem; return 0; } -- 2.25.1