On 02/24/2014 10:07 AM, Vince Weaver wrote:
>>
>> Anyway I've attached the full tail end of the trace if you want to see
>> everything that happens.
>
> and then I note there are *two* kernel page faults.
>
> perf_fuzzer-2979 [000] 161.475924: page_fault_kernel:
> address=irq_stack_union ip=copy_user_generic_string error_code=0x0
> address=0x1 ip=0xffffffff812a7d9c error_code=0x0
> perf_fuzzer-2979 [000] 161.475924: function:
> __do_page_fault
> perf_fuzzer-2979 [000] 161.475924: function:
> bad_area_nosemaphore
> perf_fuzzer-2979 [000] 161.475925: function:
> __bad_area_nosemaphore
> perf_fuzzer-2979 [000] 161.475925: function:
> no_context
> perf_fuzzer-2979 [000] 161.475925: function:
> fixup_exception
> perf_fuzzer-2979 [000] 161.475926: function:
> search_exception_tables
> perf_fuzzer-2979 [000] 161.475926: function:
> search_extable
> perf_fuzzer-2979 [000] 161.475927: function:
> copy_user_handle_tail
> perf_fuzzer-2979 [000] 161.475927: function:
> trace_do_page_fault
> perf_fuzzer-2979 [000] 161.475928: page_fault_kernel:
> address=irq_stack_union ip=copy_user_handle_tail error_code=0x0
> address=0x1 ip=0xffffffff812a92bb error_code=0x0
> perf_fuzzer-2979 [000] 161.475928: function:
> __do_page_fault
> perf_fuzzer-2979 [000] 161.475928: function:
> bad_area_nosemaphore
> perf_fuzzer-2979 [000] 161.475929: function:
> __bad_area_nosemaphore
> perf_fuzzer-2979 [000] 161.475929: function:
> no_context
> perf_fuzzer-2979 [000] 161.475929: function:
> fixup_exception
> perf_fuzzer-2979 [000] 161.475929: function:
> search_exception_tables
> perf_fuzzer-2979 [000] 161.475930: function:
> search_extable
> perf_fuzzer-2979 [000] 161.475931: function:
> perf_output_begin
> perf_fuzzer-2979 [000] 161.475931: function:
> perf_output_copy
>
> That second one is in copy_user_handle_tail()
>
Either way, it really seems like we have a case of CR2 leakage out of
the NMI context.
-hpa
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