On Mon, Oct 20, 2014 at 03:07:50PM +0400, Andrey Ryabinin wrote: > > On kernel with UBSan enabled I've got following: > > UBSan: Undefined behaviour in ../kernel/time/clockevents.c:75:34 > shift exponent 32 is to large for 32-bit type 'unsigned int' > CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.17.0-rc7+ #39 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.7.5-0-ge51488c-20140602_164612-nilsson.home.kraxel.org 04/01/2014 > 0000000000000000 0000000000000000 0000000000000001 ffffffff83003db0 > ffffffff82a30940 0000000000000020 ffffffff83003dc0 ffffffff819502e9 > ffffffff83003e40 ffffffff81950735 ffff88013f003233 0000000000000000 > Call Trace: > dump_stack (/home/andrew/linux/lib/dump_stack.c:52) > ubsan_epilogue (/home/andrew/linux/lib/ubsan.c:122) > __ubsan_handle_shift_out_of_bounds (/home/andrew/linux/lib/ubsan.c:390) > ? hpet_enable (/home/andrew/linux/arch/x86/kernel/hpet.c:862) > cev_delta2ns (/home/andrew/linux/kernel/time/clockevents.c:75 (discriminator 1)) > clockevents_config.part.2 (/home/andrew/linux/kernel/time/clockevents.c:421) > ? __clocksource_select (/home/andrew/linux/kernel/time/clocksource.c:607 /home/andrew/linux/kernel/time/clocksource.c:631) > clockevents_config_and_register (/home/andrew/linux/kernel/time/clockevents.c:440) > hpet_enable (/home/andrew/linux/arch/x86/kernel/hpet.c:305 /home/andrew/linux/arch/x86/kernel/hpet.c:891) > hpet_time_init (/home/andrew/linux/arch/x86/kernel/time.c:79) > x86_late_time_init (/home/andrew/linux/arch/x86/kernel/time.c:87) > start_kernel (/home/andrew/linux/init/main.c:637) > ? early_idt_handlers (/home/andrew/linux/arch/x86/kernel/head_64.S:344) > x86_64_start_reservations (/home/andrew/linux/arch/x86/kernel/head64.c:194) > x86_64_start_kernel (/home/andrew/linux/arch/x86/kernel/head64.c:183) > > I guess it should be 1ULL here instead of 1U: > (!ismax || evt->mult <= (1U << evt->shift))) Probably so indeed, clocks_calc_mult_shift() has max return value of 32, which will indeed trigger that overflow. -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
