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=-16.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 C0C06C43463 for ; Fri, 18 Sep 2020 02:34:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 76C4E23730 for ; Fri, 18 Sep 2020 02:34:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600396481; bh=KEdDaj2rl9n492aoW3xE+uz9UJM/LdYdz/Y1IXG2eU0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=VuR/SA4HpVQ3Acqj1eGD6ozVGJdAtmOtZ7j/HezFtU5vldQQRofcQ8mYliqC6ifve aKqBDkEWZxIUymPrViT3ymvPiOgWsEfrncDMTYr8rGWSuGbPd40P05CBQyWzHk3D0D ZCsadqF5JO8tM94qR3w+Dg8yVL1NUvPHG2sr6OBk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729630AbgIRCek (ORCPT ); Thu, 17 Sep 2020 22:34:40 -0400 Received: from mail.kernel.org ([198.145.29.99]:40766 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728940AbgIRCN3 (ORCPT ); Thu, 17 Sep 2020 22:13:29 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 18DAF23447; Fri, 18 Sep 2020 02:13:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600395208; bh=KEdDaj2rl9n492aoW3xE+uz9UJM/LdYdz/Y1IXG2eU0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=COsuqohrOHoi2t6U3G8ePGNQx2alhqNHjSwC3H8XkGOeTwGGNjjhpQxiswcMbvZCG 5xXf+EkQSwkFJjE7qkfQwdU1qD46z2s0YxYovMn9Cpwa6eRM51gIOb3vTJ5kJ+CdoB d8xFBB37rVAiw341nb2L2VJN2cVXUa4v+47uj6uc= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Wen Yang , Thomas Gleixner , Sasha Levin Subject: [PATCH AUTOSEL 4.14 057/127] timekeeping: Prevent 32bit truncation in scale64_check_overflow() Date: Thu, 17 Sep 2020 22:11:10 -0400 Message-Id: <20200918021220.2066485-57-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200918021220.2066485-1-sashal@kernel.org> References: <20200918021220.2066485-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore 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 1ce7c404d0b03..5b6f815a74ee3 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -988,9 +988,8 @@ 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