From patchwork Mon Dec 25 11:10:37 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Baolin Wang X-Patchwork-Id: 852794 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=linux-rtc-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=linaro.org header.i=@linaro.org header.b="BC1foCvB"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3z4xJY1YrLz9s4q for ; Mon, 25 Dec 2017 22:11:41 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750847AbdLYLLj (ORCPT ); Mon, 25 Dec 2017 06:11:39 -0500 Received: from mail-pg0-f66.google.com ([74.125.83.66]:40335 "EHLO mail-pg0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750806AbdLYLLi (ORCPT ); Mon, 25 Dec 2017 06:11:38 -0500 Received: by mail-pg0-f66.google.com with SMTP id k15so16897634pgr.7 for ; Mon, 25 Dec 2017 03:11:38 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id; bh=ivxjW2s1i0Wwh/h/DDdI1mVVFQRGU/mqEFiftwg6Vdw=; b=BC1foCvBimatktY/1wLoLXIUDl63Txapi0CJlJygz9jU5cAFjfharJ976QZigbHGL4 oeSLCmKeoa3AVukxD+bwu4IobAlQ0+zUKdaiYkAoJKXVROrajFDQtMdguOgm56f7VRLn Ctp1+jDKXrpTj2/fYOYj/v3UPKNGEe6JVj5V8= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=ivxjW2s1i0Wwh/h/DDdI1mVVFQRGU/mqEFiftwg6Vdw=; b=iuOmN8AtTFpszTNYWpOx1HQvBaCjHJHnZu5dAstrYhLg50XV2A19Q4npVnVoX8J9Vt LPBmsxE5aF3SpzxbS+sRml5XjGIJyJwqtthHZAJMdf3MNPQHz1rOlUlHeev75D+XVQVZ VdEoWSclmfZ9+fjJuO4gNZNLcMVu3BaUrNSXP3f7JTXgQkekYhuDqT3DOsddxog9M32/ GDLGysppCK9veSjxptFsX8NC6nzCnQYd5xc1gzqwIeoannV/4ZcLSorK8hUXHmp3rpMj yMuUcJ9i4zvnJI0L8h3pujKMtQFk47pPakiOqRO3G7Sfw6Hbio+HOM7gKpRl1PMnMA+Y upHw== X-Gm-Message-State: AKGB3mKlqEvRRcpGgOmyaiv4NvCg2hKmzIZjaMSYtJeZRYIThiIEP2LX RgkZwDsCQyY1p8YQbNuX+91vCJ1LRNk= X-Google-Smtp-Source: ACJfBou0113IxZrwbE79nYv3Bex6uQF/x5hrDpMv/kxuNcUZYESxo7xDwXqg3yjqUvYbZl1Zz6LUog== X-Received: by 10.98.214.145 with SMTP id a17mr22016766pfl.167.1514200298176; Mon, 25 Dec 2017 03:11:38 -0800 (PST) Received: from baolinwangubtpc.spreadtrum.com ([117.18.48.82]) by smtp.gmail.com with ESMTPSA id a67sm5124840pgc.60.2017.12.25.03.11.34 (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 25 Dec 2017 03:11:37 -0800 (PST) From: Baolin Wang To: a.zummo@towertech.it, alexandre.belloni@free-electrons.com Cc: arnd@arndb.de, broonie@kernel.org, linux-rtc@vger.kernel.org, linux-kernel@vger.kernel.org, baolin.wang@linaro.org Subject: [PATCH] rtc: Fix overflow when converting time64_t to rtc_time Date: Mon, 25 Dec 2017 19:10:37 +0800 Message-Id: X-Mailer: git-send-email 1.7.9.5 Sender: linux-rtc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rtc@vger.kernel.org If we convert one large time values to rtc_time, in the original formula 'days * 86400' can be overflowed in 'unsigned int' type to make the formula get one incorrect remain seconds value. Thus we can use div_s64_rem() function to avoid this situation. Signed-off-by: Baolin Wang Acked-by: Arnd Bergmann --- drivers/rtc/rtc-lib.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/drivers/rtc/rtc-lib.c b/drivers/rtc/rtc-lib.c index 1ae7da5..ad5bb21 100644 --- a/drivers/rtc/rtc-lib.c +++ b/drivers/rtc/rtc-lib.c @@ -52,13 +52,11 @@ int rtc_year_days(unsigned int day, unsigned int month, unsigned int year) */ void rtc_time64_to_tm(time64_t time, struct rtc_time *tm) { - unsigned int month, year; - unsigned long secs; + unsigned int month, year, secs; int days; /* time must be positive */ - days = div_s64(time, 86400); - secs = time - (unsigned int) days * 86400; + days = div_s64_rem(time, 86400, &secs); /* day of the week, 1970-01-01 was a Thursday */ tm->tm_wday = (days + 4) % 7;