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8352724: Verify bounds for primitive array reads in JVMCI #24200

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8352724: Verify bounds for primitive array reads in JVMCI #24200

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1bfeb51
Verify bounds for primitive array reads.
pecimuth Mar 24, 2025
7475f46
Test reads after last array element in JVMCI.
pecimuth Apr 14, 2025
3661b21
Test array reads that are partially out of bounds.
pecimuth Apr 14, 2025
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13 changes: 10 additions & 3 deletions src/hotspot/share/jvmci/jvmciCompilerToVM.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2253,14 +2253,21 @@ static jobject read_field_value(Handle obj, long displacement, jchar type_char,
if (!aligned) {
JVMCI_THROW_MSG_NULL(IllegalArgumentException, "read is unaligned");
}
if (obj->is_array()) {
// Disallow reading after the last element of an array
size_t array_length = arrayOop(obj())->length();
int lh = obj->klass()->layout_helper();
size_t size_in_bytes = array_length << Klass::layout_helper_log2_element_size(lh);
size_in_bytes += Klass::layout_helper_header_size(lh);
if ((size_t) displacement + basic_type_elemsize > size_in_bytes) {
JVMCI_THROW_MSG_NULL(IllegalArgumentException, "reading after last array element");
}
}
if (basic_type == T_OBJECT) {
if (obj->is_objArray()) {
if (displacement < arrayOopDesc::base_offset_in_bytes(T_OBJECT)) {
JVMCI_THROW_MSG_NULL(IllegalArgumentException, "reading from array header");
}
if (displacement + heapOopSize > arrayOopDesc::base_offset_in_bytes(T_OBJECT) + arrayOop(obj())->length() * heapOopSize) {
JVMCI_THROW_MSG_NULL(IllegalArgumentException, "reading after last array element");
}
if (((displacement - arrayOopDesc::base_offset_in_bytes(T_OBJECT)) % heapOopSize) != 0) {
JVMCI_THROW_MSG_NULL(IllegalArgumentException, "misaligned object read from array");
}
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46 changes: 40 additions & 6 deletions ...mci/jdk.vm.ci.runtime.test/src/jdk/vm/ci/runtime/test/TestConstantReflectionProvider.java
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
/*
* Copyright (c) 2012, 2019, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2012, 2025, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
Expand Down Expand Up @@ -41,11 +41,7 @@
import java.lang.reflect.Array;
import java.util.List;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.assertNull;
import static org.junit.Assert.assertTrue;
import static org.junit.Assert.*;

/**
* Tests for {@link ConstantReflectionProvider}. It assumes an implementation of the interface that
Expand Down Expand Up @@ -138,4 +134,42 @@ public void unboxTest() {

assertNull(constantReflection.unboxPrimitive(JavaConstant.NULL_POINTER));
}

static class ArrayConstants {
static final byte[] BYTE_ARRAY_CONST = new byte[]{0};
static final Object[] OBJECT_ARRAY_CONST = new Object[]{null};
}

@Test
public void readOnePastLastArrayElementTest() {
for (ConstantValue cv : readConstants(ArrayConstants.class)) {
if (cv.boxed != null && cv.boxed.getClass().isArray()) {
JavaKind kind = metaAccess.lookupJavaType(cv.value).getComponentType().getJavaKind();
long offset = metaAccess.getArrayBaseOffset(kind) + (long) metaAccess.getArrayIndexScale(kind) * Array.getLength(cv.boxed);
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@dougxc dougxc Apr 14, 2025 •
edited
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If I understand correctly, this tests a read of an element one past the end of the array.
Can you please also add a test for a read that is partially out-of-bounds:

long offset = 1 + metaAccess.getArrayBaseOffset(kind) + (long) metaAccess.getArrayIndexScale(kind) * (Array.getLength(cv.boxed) - 1);

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I added a test for a long read from array[array.index - 1] because adding + 1 would make the read unaligned (which is also not allowed). Please check it out.

// read array[array.length]
assertThrows(IllegalArgumentException.class, () -> {
if (kind == JavaKind.Object) {
constantReflection.getMemoryAccessProvider().readObjectConstant(cv.value, offset);
} else {
constantReflection.getMemoryAccessProvider().readPrimitiveConstant(kind, cv.value, offset, kind.getBitCount());
}
});
}
}
}

static class IntArrayConstants {
static final int[] INT_ARRAY_CONST = new int[]{0};
}

@Test
public void readPartiallyOutOfBoundsTest() {
for (ConstantValue cv : readConstants(IntArrayConstants.class)) {
JavaKind kind = metaAccess.lookupJavaType(cv.value).getComponentType().getJavaKind();
long offset = metaAccess.getArrayBaseOffset(kind) + (long) metaAccess.getArrayIndexScale(kind) * (Array.getLength(cv.boxed) - 1);
// read a long from array[array.length - 1], which is partially out of bounds
JavaKind accessKind = JavaKind.Long;
assertThrows(IllegalArgumentException.class, () -> constantReflection.getMemoryAccessProvider().readPrimitiveConstant(accessKind, cv.value, offset, accessKind.getBitCount()));
}
}
}