RFR 8050485: super() in a try block in a ctor causes VerifyError

[harold seigel]

Hi Dean,

Yes, a pathological bytecode sequence could cause a native stack 
overflow.  But there are probably multiple pathological bytecode 
sequences that could cause the JVM to run out of other resources.

The purpose of this fix is to allow well behaved tools such as NetBeans 
Profiler to work but also prevent malformed objects from being returned 
by constructors.

Harold
On 7/24/2014 2:44 PM, Dean Long wrote:
> It looks like, given a pathological bytecode sequence, that the 
> recursion would be limited only by the length of the
> bytecode sequence.  Couldn't this cause a native stack overflow crash?
>
> dl
>
> On 7/24/2014 10:55 AM, harold seigel wrote:
>> Hi,
>>
>> Please review this verifier fix for bug 8050485.
>>
>> The fix for JDK-8035119 
>> <https://bugs.openjdk.java.net/browse/JDK-8035119> broke existing 
>> tools, such as NetBeans Profiler, that generate bytecodes which place 
>> TRY blocks around constructor calls to super() and this().  The 
>> purpose of that fix was to prevent exception handlers from handling 
>> exceptions thrown from super() and this(), and returning malformed 
>> objects to the callers of the constructors.
>>
>> The NB Profiler prevents malformed objects from being returned to the 
>> constructors' callers by having the exception handlers re-throw the 
>> exceptions.
>>
>> The purpose of this fix is to allow a TRY block around a 
>> constructor's call to super() and this(), provided that all code 
>> paths in the TRY block's exception handlers terminate with a throw. 
>> This prevents malformed objects from being returned and does not 
>> break tools like NB Profiler.
>>
>> The fix works by parsing the bytecodes inside of the exception 
>> handlers, making sure that all code paths end in an 'athrow' 
>> bytecode.  Otherwise, it throws a VerifyError exception.  This 
>> parsing is only done when the verifier detects a constructor's call 
>> to super() or this() from inside of a TRY block.
>>
>> Bug:  https://bugs.openjdk.java.net/browse/JDK-8050485
>> Open webrev: http://cr.openjdk.java.net/~hseigel/bug_8050485/
>>
>> The fix was tested with the JCK lang, vm, and api/java_lang tests, 
>> the UTE verifier and quick tests, the JTREG hotspot tests, and 
>> additional tests with constructor calls to super() and this() from 
>> inside of a TRY block, including one provided by NB Profiler.
>>
>> Thanks, Harold
>