Commit 074b01a5 authored Dec 20, 2018 by ZhangXiaoxu Committed by Alexandre Belloni Jan 10, 2019

rtc: Fix UBSAN overflow warning



Users may call 'ioctl' and pass a very big value on 'tm->tm_year'.
It can be overflowed in 'int' after add 1900.
In function 'rtc_month_days' and 'mktime64', also treated it as an
'unsigned' parameter.

UBSAN: Undefined behaviour in drivers/rtc/rtc-lib.c:103:59
signed integer overflow:
2147483647 + 1900 cannot be represented in type 'int'

UBSAN: Undefined behaviour in drivers/rtc/rtc-lib.c:119:30
signed integer overflow:
2147483647 + 1900 cannot be represented in type 'int'

So, covert it to 'unsigned' explicitly.

Signed-off-by: ZhangXiaoxu <zhangxiaoxu5@huawei.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

parent 7c617e0c

drivers/rtc/lib.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -100,7 +100,7 @@ int rtc_valid_tm(struct rtc_time *tm)
		if (tm->tm_year < 70
		\|\| ((unsigned)tm->tm_mon) >= 12
		\|\| tm->tm_mday < 1
		\|\| tm->tm_mday > rtc_month_days(tm->tm_mon, tm->tm_year + 1900)
		\|\| tm->tm_mday > rtc_month_days(tm->tm_mon, ((unsigned)tm->tm_year + 1900))
		\|\| ((unsigned)tm->tm_hour) >= 24
		\|\| ((unsigned)tm->tm_min) >= 60
		\|\| ((unsigned)tm->tm_sec) >= 60)
		@@ -116,8 +116,8 @@ EXPORT_SYMBOL(rtc_valid_tm);
		*/
		time64_t rtc_tm_to_time64(struct rtc_time *tm)
		{
		return mktime64(tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday,
		tm->tm_hour, tm->tm_min, tm->tm_sec);
		return mktime64(((unsigned)tm->tm_year + 1900), tm->tm_mon + 1,
		tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec);
		}
		EXPORT_SYMBOL(rtc_tm_to_time64);

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