Move the check on the constant module/package flag to checkPool()

[ChengJin01]

The change is to move the check on the constant module/package
flag from readPool() to checkPool() to ensure a module class with
ACC_MODULE set is correctly captured/rejected as NoClassDefFoundError
prior to checkPool() during the static verification.

Internal ref 146836

Signed-off-by: Cheng Jin jincheng@ca.ibm.com

[ChengJin01]

The existing code of checking CONSTANT_Module/CONSTANT_Package in readPool() is incorrect as the the access flags of the current class has not yet been determined until VM finishes traversing the constant pool (because the access flags of class file stay right after the constant pool). So the check (intended for classes without ACC_MODULE in the access flags) should be moved to checkPool() given the check on the access flags is done prior to checkPool() (invoked by checkClass()) in j9bcutil_readClassFileBytes():

/runtime/bcutil/cfreader.c

j9bcutil_readClassFileBytes(J9PortLibrary *portLib, ... )
{...
	if ((result = readPool(classfile, data, dataEnd, segment, segmentEnd, &index, &freePointer)) != 0) { <--------
		Trc_BCU_j9bcutil_readClassFileBytes_Exit(result);
		return result;
	}
	endOfConstantPool = index;
	VERBOSE_END(ParseClassFileConstantPool);

	CHECK_EOF(8);
	classfile->accessFlags = NEXT_U16(classfile->accessFlags, index); <------- accessFlags is set after readPool()

	/* class files with the ACC_MODULE flag set cannot be loaded */
	if (((flags & BCT_MajorClassFileVersionMask) >= BCT_JavaMajorVersionShifted(9))
		&& J9_ARE_ALL_BITS_SET(classfile->accessFlags, CFR_ACC_MODULE) <---- ACC_MODULE is check here
	) {
		errorCode = J9NLS_CFR_ERR_MODULE_IS_INVALID_CLASS__ID;
		errorAction = CFR_ThrowNoClassDefFoundError;
		offset = index - data - 2;
		goto _errorFound;
	}
...
	/* Structure verification. This is "Pass 1". */
	if (0 != (flags & CFR_StaticVerification)) {
---> if(checkClass(portLib, classfile, segment, (U_32) (endOfConstantPool - data), vmVersionShifted, flags)) {
			Trc_BCU_j9bcutil_readClassFileBytes_Exit(-1);
			return -1;
		}
	}
....

checkClass(J9PortLibrary *portLib, J9CfrClassFile* classfile, U_8* segment, U_32 endOfConstantPool, U_32 vmVersionShifted, U_32 flags)
{
...
	if(checkPool(classfile, segment, (U_8*)10, &maxBootstrapMethodIndex, flags)) { <-------
		return -1;
	}

[ChengJin01]

Reviewer: @DanHeidinga
FYI: @gacholio, @tajila, @pshipton

[DanHeidinga]

looks reasonable

[DanHeidinga]

Jenkins test sanity zlinux jdk11,,jdk17