RFR: 8336833: Endless loop in Javap ClassWriter

[Adam Sotona]

On Fri, 19 Jul 2024 15:41:07 GMT, Chen Liang <liach at openjdk.org> wrote:

>> Artificially corrupted class with overflowing max - min values of `tableswitch` instruction cause infinite loop in `jdk.internal.classfile.impl.CodeImpl::inflateJumpTargets`
>> 
>> This patch fixes the overflow and adds relevant test.
>> 
>> Please review.
>> 
>> Thank you,
>> Adam
>
> src/java.base/share/classes/jdk/internal/classfile/impl/AbstractInstruction.java line 320:
> 
>> 318:             int low = code.classReader.readInt(ap + 4);
>> 319:             int high = code.classReader.readInt(ap + 8);
>> 320:             if (high < low || (long)high - low > code.codeLength >> 2) {
> 
> Maybe `Integer.toUnsignedLong(high - low)` might be clearer?

I think it is safer to convert to long beforehand.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20258#discussion_r1684570869