From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:60496 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932563AbeDKStm (ORCPT ); Wed, 11 Apr 2018 14:49:42 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Steve Best , Vaibhav Jain , Alexandre Belloni , Sasha Levin Subject: [PATCH 4.4 103/190] rtc: interface: Validate alarm-time before handling rollover Date: Wed, 11 Apr 2018 20:35:49 +0200 Message-Id: <20180411183556.601176115@linuxfoundation.org> In-Reply-To: <20180411183550.114495991@linuxfoundation.org> References: <20180411183550.114495991@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Vaibhav Jain [ Upstream commit da96aea0ed177105cb13ee83b328f6c61e061d3f ] In function __rtc_read_alarm() its possible for an alarm time-stamp to be invalid even after replacing missing components with current time-stamp. The condition 'alarm->time.tm_year < 70' will trigger this case and will cause the call to 'rtc_tm_to_time64(&alarm->time)' return a negative value for variable t_alm. While handling alarm rollover this negative t_alm (assumed to seconds offset from '1970-01-01 00:00:00') is converted back to rtc_time via rtc_time64_to_tm() which results in this error log with seemingly garbage values: "rtc rtc0: invalid alarm value: -2-1--1041528741 2005511117:71582844:32" This error was generated when the rtc driver (rtc-opal in this case) returned an alarm time-stamp of '00-00-00 00:00:00' to indicate that the alarm is disabled. Though I have submitted a separate fix for the rtc-opal driver, this issue may potentially impact other existing/future rtc drivers. To fix this issue the patch validates the alarm time-stamp just after filling up the missing datetime components and if rtc_valid_tm() still reports it to be invalid then bails out of the function without handling the rollover. Reported-by: Steve Best Signed-off-by: Vaibhav Jain Signed-off-by: Alexandre Belloni Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/rtc/interface.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) --- a/drivers/rtc/interface.c +++ b/drivers/rtc/interface.c @@ -217,6 +217,13 @@ int __rtc_read_alarm(struct rtc_device * missing = year; } + /* Can't proceed if alarm is still invalid after replacing + * missing fields. + */ + err = rtc_valid_tm(&alarm->time); + if (err) + goto done; + /* with luck, no rollover is needed */ t_now = rtc_tm_to_time64(&now); t_alm = rtc_tm_to_time64(&alarm->time); @@ -268,9 +275,9 @@ int __rtc_read_alarm(struct rtc_device * dev_warn(&rtc->dev, "alarm rollover not handled\n"); } -done: err = rtc_valid_tm(&alarm->time); +done: if (err) { dev_warn(&rtc->dev, "invalid alarm value: %d-%d-%d %d:%d:%d\n", alarm->time.tm_year + 1900, alarm->time.tm_mon + 1,