From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3wTvFp50tkzDqd7 for ; Sat, 20 May 2017 02:51:10 +1000 (AEST) Received: from pps.filterd (m0098421.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v4JGi5Bw077993 for ; Fri, 19 May 2017 12:51:06 -0400 Received: from e23smtp03.au.ibm.com (e23smtp03.au.ibm.com [202.81.31.145]) by mx0a-001b2d01.pphosted.com with ESMTP id 2ahr3jj3bd-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Fri, 19 May 2017 12:51:06 -0400 Received: from localhost by e23smtp03.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Sat, 20 May 2017 02:51:03 +1000 Received: from d23av04.au.ibm.com (d23av04.au.ibm.com [9.190.235.139]) by d23relay10.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v4JGoqkc2032126 for ; Sat, 20 May 2017 02:51:00 +1000 Received: from d23av04.au.ibm.com (localhost [127.0.0.1]) by d23av04.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id v4JGoQvj021945 for ; Sat, 20 May 2017 02:50:27 +1000 From: Vaibhav Jain To: Alessandro Zummo , Alexandre Belloni Cc: Vaibhav Jain , rtc-linux@googlegroups.com, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: [PATCH] drivers/rtc/interface.c: Validate alarm-time before handling rollover Date: Fri, 19 May 2017 22:18:55 +0530 Message-Id: <20170519164855.11747-1-vaibhav@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 --- drivers/rtc/interface.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c index fc0fa75..8cec9a0 100644 --- a/drivers/rtc/interface.c +++ b/drivers/rtc/interface.c @@ -227,6 +227,13 @@ int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm) 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); @@ -278,9 +285,9 @@ int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm) 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, -- 2.9.3