UBSAN: Undefined behaviour in kernel/time/tick-sched.c:600:9

From: Meelis Roos
Date: Fri Mar 10 2017 - 12:30:36 EST


(Retry with fixed address ox 86 list)

This HP Netserver LT6000R, quad P3 Xeon. Trying
4.11.0-rc1-00088-gec3b93a, I got the following UBSAN warning that was
not there in 4.10:

[ 14.820437] ================================================================================
[ 14.820534] UBSAN: Undefined behaviour in kernel/time/tick-sched.c:600:9
[ 14.820594] signed integer overflow:
[ 14.820645] 11567464533 + 3985952 cannot be represented in type 'long long int'
[ 14.820722] CPU: 3 PID: 135 Comm: startpar Not tainted 4.11.0-rc1-00088-gec3b93a #61
[ 14.820793] Hardware name: Hewlett Packard HP NetServer/HP System Board, BIOS 4.06.46 PW 06/25/2003
[ 14.820863] Call Trace:
[ 14.820950] ? dump_stack+0x45/0x6e
[ 14.821022] ? ubsan_epilogue+0xb/0x40
[ 14.821081] ? handle_overflow+0xb6/0xe0
[ 14.821146] ? smp_trace_apic_timer_interrupt+0x85/0x100
[ 14.821208] ? __ubsan_handle_add_overflow+0xf/0x20
[ 14.821281] ? get_cpu_idle_time_us+0x204/0x2b0
[ 14.821350] ? get_idle_time+0x57/0xb0
[ 14.821405] ? show_stat+0x217/0x10c0
[ 14.821463] ? seq_open+0x33/0xb0
[ 14.821519] ? __d_alloc+0x149/0x2c0
[ 14.821574] ? get_iowait_time+0xb0/0xb0
[ 14.821628] ? single_open+0x4d/0xb0
[ 14.821685] ? single_open_size+0x37/0xc0
[ 14.821748] ? path_openat+0x7d5/0x1bd0
[ 14.821804] ? seq_read+0xca/0x6f0
[ 14.821872] ? _copy_to_user+0x5e/0x90
[ 14.821937] ? cp_new_stat64+0x108/0x130
[ 14.821991] ? __seq_open_private+0x80/0x80
[ 14.822062] ? proc_reg_read+0x7c/0x120
[ 14.822117] ? proc_reg_write+0x120/0x120
[ 14.822172] ? __vfs_read+0x3e/0x240
[ 14.822228] ? vfs_read+0x92/0x1b0
[ 14.822282] ? SyS_read+0x45/0xa0
[ 14.822338] ? do_fast_syscall_32+0xb9/0x220
[ 14.822395] ? entry_SYSENTER_32+0x47/0x71
[ 14.822447]
================================================================================


--
Meelis Roos (mroos@xxxxxxxx)