RFR(xxs): 8176140: Crashes or timeouts during error reporting may lead to infinitely repeated error logs until ErrorLogTimeout is hit

[Chris Plummer]

On 3/8/17 6:27 PM, David Holmes wrote:
> Hi Thomas,
>
> On 9/03/2017 4:38 AM, Thomas Stüfe wrote:
>> Hi all,
>>
>> please review this tiny fix.
>>
>> Issue: https://bugs.openjdk.java.net/browse/JDK-8176140
>>
>> Webrev:
>> http://cr.openjdk.java.net/~stuefe/webrevs/8176140-Crashes-or-timeouts-during-error-reporting-may-lead-to-infinitely-repeated-error-logs-until-ErrorLogTimeout-is-hit/jdk10-webrev.00/webrev/ 
>>
>>
>> Basically, the error reporting had this bug where a secondary crash (or,
>> after JDK-8166944, a timeout) could lead to an error log with infinitely
>> repeated content. In practice, one would hit either the maximum stack 
>> depth
>> of the reporting thread or the ErrorLogTimeout.
>>
>> This would happen if the crash were to happen inside
>> VMError::report_and_die(), after the reporting is done
>> |VMError::report(&log, true)| and before the |log_done| flag is set. 
>> This
>> is a very small window, but Chris was able to trigger this bug by
>> introducing an error inside an ubiquitous base function (malloc), so 
>> it is
>> not just theoretical.
>>
>> The fix is simply to set log_done right after the VMError::report() 
>> call.
>
> Seems reasonable.
+1. Thanks for fixing.

Chris
>
> Thanks,
> David
> -----
>
>> Thanks & Kind Regards, Thomas
>>