From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965498AbeCSXsj (ORCPT ); Mon, 19 Mar 2018 19:48:39 -0400 Received: from mail.bootlin.com ([62.4.15.54]:54262 "EHLO mail.bootlin.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964813AbeCSXsd (ORCPT ); Mon, 19 Mar 2018 19:48:33 -0400 From: Alexandre Belloni To: linux-rtc@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Alexandre Belloni Subject: [PATCH 1/6] rtc: hctosys: Ensure system time doesn't overflow time_t Date: Tue, 20 Mar 2018 00:48:12 +0100 Message-Id: <20180319234817.16199-1-alexandre.belloni@bootlin.com> X-Mailer: git-send-email 2.16.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 32bit platforms, time_t is still a signed 32bit long. If it is overflowed, userspace and the kernel cant agree on the current system time. This causes multiple issues, in particular with systemd: https://github.com/systemd/systemd/issues/1143 A good workaround is to simply avoid using systohc which is something I greatly encourage as the time is better set by userspace. However, many distribution enable it and use systemd which is rendering the system unusable in case the RTC holds a date after 2038 (and more so after 2106). Many drivers have workaround for this case and they should be eliminated so there is only one place left to fix when userspace is able to cope with dates after the 31bit overflow. Signed-off-by: Alexandre Belloni --- drivers/rtc/hctosys.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/rtc/hctosys.c b/drivers/rtc/hctosys.c index e1cfa06810ef..e79f2a181ad2 100644 --- a/drivers/rtc/hctosys.c +++ b/drivers/rtc/hctosys.c @@ -49,6 +49,11 @@ static int __init rtc_hctosys(void) tv64.tv_sec = rtc_tm_to_time64(&tm); +#if BITS_PER_LONG == 32 + if (tv64.tv_sec > INT_MAX) + goto err_read; +#endif + err = do_settimeofday64(&tv64); dev_info(rtc->dev.parent, -- 2.16.2