Re: [peterz-queue:perf/core] [perf/x86/rapl] 90942140bb: UBSAN:array-index-out-of-bounds_in_arch/x86/events/rapl.c

[Liang, Kan]

On 2024-09-11 5:45 a.m., Peter Zijlstra wrote:
> On Wed, Sep 11, 2024 at 04:32:13PM +0800, kernel test robot wrote:
>>
>>
>> Hello,
>>
>> kernel test robot noticed "UBSAN:array-index-out-of-bounds_in_arch/x86/events/rapl.c" on:
>>
>> commit: 90942140bb6cc7e9a41d5927c7617ee522896f7a ("perf/x86/rapl: Move the pmu allocation out of CPU hotplug")
>> https://git.kernel.org/cgit/linux/kernel/git/peterz/queue.git perf/core
>>
>> in testcase: boot
>>
>> compiler: clang-18
>> test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G
>>
>> (please refer to attached dmesg/kmsg for entire log/backtrace)
>>
>>
>> +-----------------------------------------------------------+------------+------------+
>> |                                                           | c206df6d69 | 90942140bb |
>> +-----------------------------------------------------------+------------+------------+
>> | UBSAN:array-index-out-of-bounds_in_arch/x86/events/rapl.c | 0          | 12         |
>> +-----------------------------------------------------------+------------+------------+
>>
>>
>> If you fix the issue in a separate patch/commit (i.e. not just a new version of
>> the same patch/commit), kindly add following tags
>> | Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>
>> | Closes: https://lore.kernel.org/oe-lkp/202409111521.c7c6d56f-lkp@xxxxxxxxx
>>
>>
>> [   22.115286][    T1] ------------[ cut here ]------------
>> [   22.115957][    T1] UBSAN: array-index-out-of-bounds in arch/x86/events/rapl.c:685:3
> 
> That is:
> 
> 		rapl_pmus->pmus[topology_logical_die_id(cpu)] = pmu;
> 
> Which is scaled like:
> 
> 	int nr_rapl_pmu = topology_max_packages() * topology_max_dies_per_package();
> 
> And that isn't new in that patch, just moved around.
>

The error commit is still the old one which doesn't include the fix of
the issue reported by Dhananjay.
https://lore.kernel.org/lkml/88fa2064-c054-4833-872c-0cf5ff1e3609@xxxxxxx/

I think it should be the same issue.

> Kan, as it happens these two patches got zapped by Ingo because they
> conflict with that rapl patch from perf/urgent and he merged perf/urgent
> into perf/core.
> 
> I was going to rebase these two patches on top, but given the above, can
> you have a look instead?
> 
> 

Sure, I will work with Oliver on the issue, and resend the patch to
support rapl.

Thanks,
Kan