RFR: 8377512: AOT cache creation fails with invalid native pointer [v3]
Ioi Lam
iklam at openjdk.org
Thu Feb 26 02:14:29 UTC 2026
> Since JDK 25, we have two bugs that cause a pointer to an excluded class to be referenced by a cached heap object.
>
> [1] Method references to excluded classes:
>
>
> interface A {
> Object get();
> }
> ...
> A a = ShouldBeExcluded::new; // line 1
>
>
> [2] Invocation of a `MethodHandle` whose `MethodType` includes an excluded class:
>
>
> MethodHandle constructorHandle =
> MethodHandles.lookup().unreflectConstructor(ShouldBeExcluded.class.getConstructor());
> // The JVM rewrites the following invoke() from
> // invokevirtual <java/lang/invoke/MethodHandle.invoke()LShouldBeExcluded;>
> // to
> // invokehandle <java/lang/invoke/MethodHandle.invoke()LShouldBeExcluded;>
> ShouldBeExcluded o = (ShouldBeExcluded)constructorHandle.invoke(); // line 2
>
>
> In the above examples, during the training run, the AOT configuration file records the fact that the constant pool entries used by line 1 and line 2 have been resolved. Normally, these references are resolved by AOTConstantPoolResolver during the assembly phase (to improve start-up time).
>
> However, resolving these 2 entries would cause an invalid `MethodType` that references the `ShouldBeExcluded` class to be add into `MethodType::internTable`. Once this happens, it's very difficult for to recover from.
>
> Therefore, this PR tries to avoid adding such invalid `MethodType` by avoiding the resolution of such constant pool entries.
>
> Thanks to folks at Azul from coming up with the reproducer.
Ioi Lam has updated the pull request incrementally with one additional commit since the last revision:
Added asserts for the correctness of calling SystemDictionaryShared::should_be_excluded in the previous commit
-------------
Changes:
- all: https://git.openjdk.org/jdk/pull/29825/files
- new: https://git.openjdk.org/jdk/pull/29825/files/3f12ba5e..32efa79f
Webrevs:
- full: https://webrevs.openjdk.org/?repo=jdk&pr=29825&range=02
- incr: https://webrevs.openjdk.org/?repo=jdk&pr=29825&range=01-02
Stats: 11 lines in 1 file changed: 10 ins; 0 del; 1 mod
Patch: https://git.openjdk.org/jdk/pull/29825.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/29825/head:pull/29825
PR: https://git.openjdk.org/jdk/pull/29825
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