UBSAN: Undefined behaviour in arch/x86/events/intel/p6.c:116:29

[Meelis Roos]

While testing 5.4 on a Dell D600 (32-bit), I noticed the old UBSAN warnings from p6 perf events.
I remember having seen these warnings on other p6 era computers too.

[    2.795167] ================================================================================
[    2.795206] UBSAN: Undefined behaviour in arch/x86/events/intel/p6.c:116:29
[    2.795235] index 8 is out of range for type 'u64 [8]'
[    2.795265] CPU: 0 PID: 1 Comm: swapper Not tainted 5.4.0-03419-g386403a115f9-dirty #18
[    2.795266] Hardware name: Dell Computer Corporation Latitude D600                   /0X2034, BIOS A16 06/29/2005
[    2.795268] Call Trace:
[    2.795283]  dump_stack+0x16/0x19
[    2.795290]  ubsan_epilogue+0xb/0x29
[    2.795293]  __ubsan_handle_out_of_bounds.cold+0x43/0x48
[    2.795299]  ? sysfs_add_file_mode_ns+0xad/0x180
[    2.795304]  p6_pmu_event_map+0x3b/0x50
[    2.795306]  is_visible+0x25/0x30
[    2.795308]  ? collect_events+0x150/0x150
[    2.795310]  internal_create_group+0xd8/0x3e0
[    2.795312]  ? collect_events+0x150/0x150
[    2.795314]  internal_create_groups.part.0+0x34/0x80
[    2.795317]  sysfs_create_groups+0x10/0x20
[    2.795321]  device_add+0x536/0x5a0
[    2.795326]  ? kvasprintf_const+0x59/0x90
[    2.795331]  ? kfree_const+0xf/0x30
[    2.795334]  ? kobject_set_name_vargs+0x6a/0xa0
[    2.795338]  pmu_dev_alloc+0x8e/0xe0
[    2.795344]  perf_event_sysfs_init+0x40/0x78
[    2.795346]  ? stack_map_init+0x17/0x17
[    2.795347]  do_one_initcall+0x7a/0x1b3
[    2.795351]  ? do_early_param+0x75/0x75
[    2.795354]  kernel_init_freeable+0x1ae/0x230
[    2.795357]  ? rest_init+0x6d/0x6d
[    2.795359]  kernel_init+0x9/0xf3
[    2.795361]  ? rest_init+0x6d/0x6d
[    2.795363]  ret_from_fork+0x2e/0x38
[    2.795364] ================================================================================
[    2.795396] ================================================================================
[    2.795427] UBSAN: Undefined behaviour in arch/x86/events/intel/p6.c:116:29
[    2.795456] load of address (ptrval) with insufficient space
[    2.795483] for an object of type 'const u64'
[    2.795510] CPU: 0 PID: 1 Comm: swapper Not tainted 5.4.0-03419-g386403a115f9-dirty #18
[    2.795511] Hardware name: Dell Computer Corporation Latitude D600                   /0X2034, BIOS A16 06/29/2005
[    2.795512] Call Trace:
[    2.795514]  dump_stack+0x16/0x19
[    2.795517]  ubsan_epilogue+0xb/0x29
[    2.795519]  ubsan_type_mismatch_common.cold+0xd6/0xdb
[    2.795522]  __ubsan_handle_type_mismatch_v1+0x2d/0x40
[    2.795524]  p6_pmu_event_map+0x4b/0x50
[    2.795525]  is_visible+0x25/0x30
[    2.795527]  ? collect_events+0x150/0x150
[    2.795529]  internal_create_group+0xd8/0x3e0
[    2.795531]  ? collect_events+0x150/0x150
[    2.795533]  internal_create_groups.part.0+0x34/0x80
[    2.795536]  sysfs_create_groups+0x10/0x20
[    2.795537]  device_add+0x536/0x5a0
[    2.795540]  ? kvasprintf_const+0x59/0x90
[    2.795542]  ? kfree_const+0xf/0x30
[    2.795543]  ? kobject_set_name_vargs+0x6a/0xa0
[    2.795546]  pmu_dev_alloc+0x8e/0xe0
[    2.795548]  perf_event_sysfs_init+0x40/0x78
[    2.795550]  ? stack_map_init+0x17/0x17
[    2.795551]  do_one_initcall+0x7a/0x1b3
[    2.795553]  ? do_early_param+0x75/0x75
[    2.795556]  kernel_init_freeable+0x1ae/0x230
[    2.795558]  ? rest_init+0x6d/0x6d
[    2.795560]  kernel_init+0x9/0xf3
[    2.795561]  ? rest_init+0x6d/0x6d
[    2.795563]  ret_from_fork+0x2e/0x38
[    2.795565] ================================================================================


--
Meelis Roos <mroos@xxxxxxxx>