Re: perf_fuzzer compiled for x32 causes reboot

From: H. Peter Anvin
Date: Mon Feb 24 2014 - 12:43:36 EST


On 02/24/2014 09:41 AM, Vince Weaver wrote:
> On Mon, 24 Feb 2014, Vince Weaver wrote:
>
>> I do note that
>> perf_callchain_user();
>>
>> Does
>> fp = (void __user *)regs->bp;
>>
>> ...
>>
>> bytes = copy_from_user_nmi(&frame, fp, sizeof(frame));
>>
>>
>> And in my particular executable RBP has nothing to do with a frame
>> pointer, but is instead being used as a general purpose register.
>
> and as a reminder, I'm seeing this on an x32 executable, so
> perf_callchain_user32() is probably coming into play.
>
> So maybe it is an x32 issue after all.
>

No.

if (!test_thread_flag(TIF_IA32))
return 0;

TIF_IA32 is clear for an x32 process.

-hpa

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