[PATCH] RTC class: error checks

The rtc_is_valid_tm() routine needs to treat some of the fields it checks as
unsigned, to prevent wrongly accepting invalid rtc_time structs; this is the
same approach used elsewhere in the RTC code for such tests.

Conversely, rtc_proc_show() is missing one invalid-day-of-month test that
rtc_is_valid_tm() makes: there is no day zero.

Signed-off-by: David Brownell <[e-mail]>
Cc: Alessandro Zummo <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/rtc/rtc-lib.c

···
 int rtc_valid_tm(struct rtc_time *tm)
 {
 	if (tm->tm_year < 70
-		|| tm->tm_mon >= 12
+		|| ((unsigned)tm->tm_mon) >= 12
 		|| tm->tm_mday < 1
 		|| tm->tm_mday > rtc_month_days(tm->tm_mon, tm->tm_year + 1900)
-		|| tm->tm_hour >= 24
-		|| tm->tm_min >= 60
-		|| tm->tm_sec >= 60)
+		|| ((unsigned)tm->tm_hour) >= 24
+		|| ((unsigned)tm->tm_min) >= 60
+		|| ((unsigned)tm->tm_sec) >= 60)
 		return -EINVAL;
 
 	return 0;

drivers/rtc/rtc-proc.c

···
 			seq_printf(seq, "%02d-", alrm.time.tm_mon + 1);
 		else
 			seq_printf(seq, "**-");
-		if ((unsigned int)alrm.time.tm_mday <= 31)
+		if (alrm.time.tm_mday && (unsigned int)alrm.time.tm_mday <= 31)
 			seq_printf(seq, "%02d\n", alrm.time.tm_mday);
 		else
 			seq_printf(seq, "**\n");