On Tue, 24 Oct 2023 17:01:35 GMT, Jorn Vernee <jver...@openjdk.org> wrote:
> The result of `FindClass` is a local JNI handle (in > `find_class_from_class_loader`, called from `jni_FindClass` [1]). As such, we > need to wrap the return value of `FindClass` in a global reference when > storing it inside fallbackLinker.c. > > While investigating this, I also noticed an existing bug in > `JNIHandles::handle_type`. This method is used from the implementation of > `GetObjectRefType` ([2]), and from the implementation of `-Xcheck:jni` code. > The former specifies that `JNIInvalidRefType` is a valid return value, and > the latter compares the result against `JNIInvalidRefType`. However, if the > handle is not any valid type, the implementation bottoms out in a > `ShouldNotReachHere()`, meaning `JNIHandles::handle_type` can never return > `JNIInvalidRefType`. I've fixed this by letting the enclosing if/else chain > fall through to just returning the default result, which is > `JNIInvalidRefType`. In that case, I observe the expected stack trace when > running with `-Xcheck:jni`. For example: > > > FATAL ERROR in native method: Bad global or local ref passed to JNI > at > jdk.internal.foreign.abi.fallback.LibFallback.doDowncall(java.base@22-internal/Native > Method) > at > jdk.internal.foreign.abi.fallback.LibFallback.doDowncall(java.base@22-internal/LibFallback.java:94) > at > jdk.internal.foreign.abi.fallback.FallbackLinker.doDowncall(java.base@22-internal/FallbackLinker.java:197) > at > java.lang.invoke.LambdaForm$DMH/0x000001b585008000.invokeStaticInit(java.base@22-internal/LambdaForm$DMH) > at > java.lang.invoke.LambdaForm$MH/0x000001b585029400.invoke(java.base@22-internal/LambdaForm$MH) > at > java.lang.invoke.LambdaForm$MH/0x000001b58502d000.invokeExact_MT(java.base@22-internal/LambdaForm$MH) > at TestUpcallDeopt.payload(TestUpcallDeopt.java:93) > at TestUpcallDeopt.main(TestUpcallDeopt.java:84) > at > java.lang.invoke.LambdaForm$DMH/0x000001b585006800.invokeStatic(java.base@22-internal/LambdaForm$DMH) > at > java.lang.invoke.LambdaForm$MH/0x000001b58502a800.invoke(java.base@22-internal/LambdaForm$MH) > at > java.lang.invoke.Invokers$Holder.invokeExact_MT(java.base@22-internal/Invokers$Holder) > at > jdk.internal.reflect.DirectMethodHandleAccessor.invokeImpl(java.base@22-internal/DirectMethodHandleAccessor.java:154) > at > jdk.internal.reflect.DirectMethodHandleAccessor.invoke(java.base@22-internal/DirectMethodHandleAccessor.java:103) > at > java.lang.reflect.Method.invoke(java.base@22-internal/Method.java:580... This pull request has now been integrated. Changeset: 3885dc5b Author: Jorn Vernee <jver...@openjdk.org> URL: https://git.openjdk.org/jdk/commit/3885dc5b9acf08dc90397ab02b814bc72d7b4ed5 Stats: 38 lines in 7 files changed: 22 ins; 6 del; 10 mod 8318737: Fallback linker passes bad JNI handle Reviewed-by: alanb ------------- PR: https://git.openjdk.org/jdk/pull/16349
