(M) RFR: 8200167: Validate more special case invocations (original) (raw)

David Holmes david.holmes at oracle.com
Tue Apr 17 08:48:53 UTC 2018

Bug: https://bugs.openjdk.java.net/browse/JDK-8200167 webrev: http://cr.openjdk.java.net/~dholmes/8200167/webrev/

Credit to John Rose and Vladimir Ivanov for the form of the MH fix; and to Tobias Hartmann for the C1 fix. Their help was very much appreciated (and needed!).

tl;dr version: there are some places where badly formed interface method calls (which are not detected by the verifier) were missing runtime checks on the type of the receiver. Similar issues have been fixed in the past and this was a remaining hole in relation to invokespecial semantics and interface calls via MethodHandles. It also turned out there was an issue in C1 that affected direct invokespecial calls.

Description of changes:

Added a new form LF_INVSPECIAL_IFC for invokespecial of interface methods.

Renamed callerClass parameter to boundCallerClass, where it originates from findBoundCallerClass. The name "callerClass" is misleading because most of the time it is NULL!

In getDirectMethodCommon, pass the actual caller class (lookupClass) to DirectMethodHandle.make. And correct the comment about restrictReceiver.

DirectMethodHandle.make now takes a callerClass parameter (which may be null).

DirectMethodHandle make "receiver" parameter is renamed "refc" as it is not the receiver (it's the resolved type of the method holder ie REFC).

The Special subclass now takes a "checkClass" parameter which is either refc, or callerClass. This is what we will check the receiver against.

In preparedLambdaForm we switch from LF_INVSPECIAL to LF_INVSPECIAL_IFC if the target method is in an interface.

In makePreparedLambdaForm we augment the needsReceiverCheck test to include LF_INVSPECIAL_IFC. (So we will not be doing a new receiver type check on all invokespecials, just those involving interface methods.)

Added DMH.checkReceiver which is overridden by both the Special and Interface subclasses.

Don't optimize away the checkcast when it is an invokespecial receiver check.

(I've moved this test back and forth between hotspot/runtime and j.l.invoke as it spans direct calls and MH calls. But I think on balance it lands better here.)

The test sets up direct interface method calls for which invokespecial is generated by javac, and similarly it creates MethodHandles with invokespecial semantics. The should-not-throw cases are trivial. The should-throw cases involve MH wizardry.

The test is broken into three parts to check the behaviour on first use (when the method has to be initially resolved); on second use (to test we don't use the cpcache in a way that is invalid); and again after forcing JIT compilation of the calls.

The test is run 5 times to exercise the interpreter (yes the multiple runs internal to the test are redundant in this case, but it's much simpler to just run it all than try to work out what needs to be run); the three variants of using C1, plus a C2 only run.

Testing:

Plus some related closed tests.

Thanks, David

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