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

[Meelis Roos]

(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)