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 C52B6C43467 for ; Fri, 18 Sep 2020 02:27:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 88FF1235F7 for ; Fri, 18 Sep 2020 02:27:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600396020; bh=8o9zybgIuHAYYolfy9YI06KREygAviigU0xC/9gLius=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=fRejCIFag7A3BkK/bTQviELh/7XL/oPl7ivy5VQkUMTnJbL58teCBnh93JqY3bvs9 ih0Q6VNe34xmUZ5cOIW/VUVcNu+Jn5v674ZUovk410rjAEVC0Rs0PovGveljL9gX9/ MqbmricKJ4HVtwtKXFwflFhB+Wvm3R0DiTiHCDp8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728153AbgIRC07 (ORCPT ); Thu, 17 Sep 2020 22:26:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:45112 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729294AbgIRCPv (ORCPT ); Thu, 17 Sep 2020 22:15:51 -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 D22152396F; Fri, 18 Sep 2020 02:15:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600395351; bh=8o9zybgIuHAYYolfy9YI06KREygAviigU0xC/9gLius=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=d8qoOm6zNWPuo9Bp40Hw1Qm3L4oVf6O/6b3pyoWf0m81pZzj7lXBbDxJnEF5U8DPn +GODJiPHHt1aEatjrgqiD+dqqtTW290GCadrYapB8wCk65sHoyFDb1T4P14/C6lNYB aPjY+ScfVReG/6y+C5ofnR6JCrV9DxHUS7a3pKsM= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Wen Yang , Thomas Gleixner , Sasha Levin Subject: [PATCH AUTOSEL 4.9 46/90] timekeeping: Prevent 32bit truncation in scale64_check_overflow() Date: Thu, 17 Sep 2020 22:14:11 -0400 Message-Id: <20200918021455.2067301-46-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200918021455.2067301-1-sashal@kernel.org> References: <20200918021455.2067301-1-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 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