RFR (S) 8042660: vm/mlvm/anonloader/stress/byteMutation failed with: assert(index >=0 && index < _length) failed: symbol index overflow

[Karen Kinnear]

Harold,

Looks good for the assertion you hit.
Thank you for the fix and the extensive testing!

And thank you for walking me privately through -
spec reference to requiring at least one code point which means “” is not a valid name or signature
and having the logic under the >= JAVA_7_VERSION since that is where we added verification that this
was the right type of signature.

And thank you for adding the test for the empty method name - if I understand correctly, that is testing
existing code in verify_legal_method_name. 

I believe if you were to turn off verification you could
run into the assertion under JVM_CONSTANT_Methodref “bad method name”. Perhaps instead
of an assertion there you could check if name length == 0 or something so we do the init check
properly but don’t assert/crash.

thanks,
Karen

> On Dec 21, 2015, at 1:35 PM, harold seigel <harold.seigel at oracle.com> wrote:
> 
> Hi,
> 
> Please review this small change to fix bug 8042660 <https://bugs.openjdk.java.net/browse/JDK-8042660>.
> 
> The code in ClassFileParser::parse_constant_pool() that handles CONSTANT_NameAndType and CONSTANT_*Ref assumes that the constant pool strings they reference are valid names and signatures because they are valid Utf8 strings.  But, "" is a valid Utf8 string but not a valid name or signature.  Assuming that the strings were of non-zero length caused crashes when test byteMutation specified zero length strings.  This fix adds checks for strings of zero length and throws ClassFormatError exceptions, preventing the JVM crashes.
> 
> Open webrev: http://cr.openjdk.java.net/~hseigel/bug_8042660/
> 
> JBS Bug: https://bugs.openjdk.java.net/browse/JDK-8042660
> 
> The fix was tested with JCK Lang, VM, and API java_lang tests, the UTE quick and split verifier tests, and the hotspot, JDK vm, java/io, java/lang, and java/util JTreg tests, and the tests included in this RFR.
> 
> Thanks, Harold