From 00b912b0c88e690b1662067497182454357b18b0 Mon Sep 17 00:00:00 2001 From: Daniel Axtens Date: Tue, 15 Dec 2015 18:09:14 +1100 Subject: powerpc: Remove broken GregorianDay() GregorianDay() is supposed to calculate the day of the week (tm->tm_wday) for a given day/month/year. In that calcuation it indexed into an array called MonthOffset using tm->tm_mon-1. However tm_mon is zero-based, not one-based, so this is off-by-one. It also means that every January, GregoiranDay() will access element -1 of the MonthOffset array. It also doesn't appear to be a correct algorithm either: see in contrast kernel/time/timeconv.c's time_to_tm function. It's been broken forever, which suggests no-one in userland uses this. It looks like no-one in the kernel uses tm->tm_wday either (see e.g. drivers/rtc/rtc-ds1305.c:319). tm->tm_wday is conventionally set to -1 when not available in hardware so we can simply set it to -1 and drop the function. (There are over a dozen other drivers in drivers/rtc that do this.) Found using UBSAN. Cc: Andrey Ryabinin Cc: Andrew Morton # as an example of what UBSan finds. Cc: Alessandro Zummo Cc: Alexandre Belloni Cc: rtc-linux@googlegroups.com Signed-off-by: Daniel Axtens Acked-by: Alexandre Belloni Signed-off-by: Michael Ellerman --- arch/powerpc/include/asm/time.h | 1 - 1 file changed, 1 deletion(-) (limited to 'arch/powerpc/include/asm/time.h') diff --git a/arch/powerpc/include/asm/time.h b/arch/powerpc/include/asm/time.h index 10fc784a2ad4..2d7109a8d296 100644 --- a/arch/powerpc/include/asm/time.h +++ b/arch/powerpc/include/asm/time.h @@ -27,7 +27,6 @@ extern struct clock_event_device decrementer_clockevent; struct rtc_time; extern void to_tm(int tim, struct rtc_time * tm); -extern void GregorianDay(struct rtc_time *tm); extern void tick_broadcast_ipi_handler(void); extern void generic_calibrate_decr(void); -- cgit v1.2.3