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fix: validate compact JSONB number continuations #7822

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fix: validate compact JSONB number continuations #7822

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d625147
fix: validate compact JSONB number continuations
DarrenChangJR Aug 24, 2026
c38a68f
fix: cover compact JSONB reader fast paths
DarrenChangJR Aug 25, 2026
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21 changes: 13 additions & 8 deletions core/src/main/java/com/alibaba/fastjson2/JSONReaderJSONB.java
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Original file line number Diff line number Diff line change
Expand Up @@ -215,15 +215,21 @@ public int readLength() {
return type;
}

private static int getIntByte(byte[] bytes, int offset, int type) {
private int getIntByte(byte[] bytes, int offset, int type) {
if (offset >= end) {
throw outOfBoundsCheckFromToIndex(offset, end);
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}
return ((type - BC_INT32_BYTE_ZERO) << 8) + (bytes[offset] & 0xFF);
}

private static int getInt3(byte[] bytes, int offset, int type) {
return ((type - BC_INT32_SHORT_ZERO) << 16) + (getShortBE(bytes, offset) & 0xFFFF);
}

private static int getLongByte(byte[] bytes, int offset, int type) {
private int getLongByte(byte[] bytes, int offset, int type) {
if (offset >= end) {
throw outOfBoundsCheckFromToIndex(offset, end);
}
return ((type - BC_INT64_BYTE_ZERO) << 8) + (bytes[offset] & 0xFF);
}

Expand Down Expand Up @@ -451,12 +457,12 @@ public Map<String, Object> readObject() {
} else if (isInt32Byte(valueType)) {
value = getIntByte(bytes, offset + 1, valueType);
offset += 2;
} else if (isInt32Short(valueType) && offset + 1 < end) {
} else if (isInt32Short(valueType) && offset + 2 < end) {
int int32Value = getInt3(bytes, offset + 1, valueType);
offset += 3;
value = int32Value;
} else if (valueType == BC_INT32 && offset + 3 < end) {
int int32Value = getIntBE(bytes, offset + 1);
} else if (valueType == BC_INT32) {
int int32Value = getIntBE(bytes, check3(offset + 1, end));
offset += 5;
value = int32Value;
} else {
Expand Down Expand Up @@ -1637,7 +1643,7 @@ public long readTypeHashCode() {
offset++;
typelen = type;
} else {
typelen = ((type - BC_INT32_BYTE_ZERO) << 8) + (bytes[offset + 1] & 0xFF);
typelen = getIntByte(bytes, offset + 1, type);
offset += 2;
}

Expand Down Expand Up @@ -1729,8 +1735,7 @@ public long readTypeHashCode0() {
typeIndex = strtype;
} else if (strtype <= BC_INT32_BYTE_MAX) {
offset++;
typeIndex = ((strtype - BC_INT32_BYTE_ZERO) << 8)
+ (bytes[offset++] & 0xFF);
typeIndex = getIntByte(bytes, offset++, strtype);
} else {
typeIndex = readInt32Value();
}
Expand Down
147 changes: 147 additions & 0 deletions core/src/test/java/com/alibaba/fastjson2/jsonb/JSONBCompactNumberBoundsTest.java
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Original file line number Diff line number Diff line change
@@ -0,0 +1,147 @@
package com.alibaba.fastjson2.jsonb;

import com.alibaba.fastjson2.JSONB;
import com.alibaba.fastjson2.JSONException;
import com.alibaba.fastjson2.JSONReader;
import org.junit.jupiter.api.Tag;
import org.junit.jupiter.api.Test;

import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.function.Function;

import static com.alibaba.fastjson2.JSONB.Constants.*;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertThrows;

@Tag("jsonb")
public class JSONBCompactNumberBoundsTest {
@Test
public void truncatedCompactInt32Byte() {
byte[] bytes = {BC_INT32_BYTE_ZERO};
assertMalformedAcrossNumberReaders(bytes);
assertMalformedSlice(bytes);
}

@Test
public void truncatedCompactInt32Short() {
assertMalformedAcrossNumberReaders(new byte[]{BC_INT32_SHORT_ZERO});
assertMalformedAcrossNumberReaders(new byte[]{BC_INT32_SHORT_ZERO, 0});
}

@Test
public void truncatedCompactInt64Byte() {
byte[] bytes = {BC_INT64_BYTE_ZERO};
assertMalformedAcrossNumberReaders(bytes);
assertMalformedSlice(bytes);
}

@Test
public void truncatedCompactInt64Short() {
assertMalformedAcrossNumberReaders(new byte[]{BC_INT64_SHORT_ZERO});
assertMalformedAcrossNumberReaders(new byte[]{BC_INT64_SHORT_ZERO, 0});
}

@Test
public void truncatedCompactLength() {
assertThrows(JSONException.class, () -> JSONB.parse(new byte[]{BC_ARRAY, BC_INT32_BYTE_ZERO}));
assertThrows(JSONException.class, () -> JSONB.parse(new byte[]{BC_STR_UTF8, BC_INT32_BYTE_ZERO}));
}

@Test
public void truncatedCompactTypeMetadata() {
byte[] typeNameLength = {
BC_TYPED_ANY, BC_STR_ASCII, (byte) (BC_INT32_BYTE_ZERO + 1)
};
assertThrows(JSONException.class, () -> JSONB.parse(typeNameLength));
assertMalformedSlice(typeNameLength);

byte[] typeIndex = {BC_INT32_BYTE_ZERO};
assertMalformed(typeIndex, JSONReader::readTypeHashCode);
assertMalformedSlice(typeIndex, JSONReader::readTypeHashCode);
}

@Test
public void truncatedCompactValuesInContainers() {
assertThrows(JSONException.class, () -> JSONB.parse(new byte[]{
(byte) (BC_ARRAY_FIX_MIN + 1), BC_INT32_BYTE_ZERO
}));
assertThrows(JSONException.class, () -> JSONB.parse(new byte[]{
BC_OBJECT, BC_STR_ASCII_FIX_1, 'a', BC_INT32_BYTE_ZERO
}));

byte[] int32Short = {
BC_OBJECT, BC_STR_ASCII_FIX_1, 'a', BC_INT32_SHORT_ZERO, 0
};
assertThrows(JSONException.class, () -> JSONB.parseObject(int32Short));

byte[] int32 = {
BC_OBJECT, BC_STR_ASCII_FIX_1, 'a', BC_INT32, 0, 0, 0
};
assertThrows(JSONException.class, () -> JSONB.parseObject(int32));

assertMalformedSlice(new byte[]{
BC_OBJECT, BC_STR_ASCII_FIX_1, 'a', BC_INT32_SHORT_ZERO, 0
});
assertMalformedSlice(new byte[]{
BC_OBJECT, BC_STR_ASCII_FIX_1, 'a', BC_INT32, 0, 0, 0
});
}

@Test
public void validCompactNumberBoundaries() {
Number[] values = {
-2048, 2047,
-262144, 262143,
-2048L, 2047L,
-262144L, 262143L
};
for (Number value : values) {
assertEquals(value, JSONB.parse(JSONB.toBytes(value)));
}

assertEquals(1, JSONB.parseObject(new byte[]{
BC_OBJECT, BC_STR_ASCII_FIX_1, 'a', BC_INT32_SHORT_ZERO, 0, 1, BC_OBJECT_END
}).get("a"));
assertEquals(1, JSONB.parseObject(new byte[]{
BC_OBJECT, BC_STR_ASCII_FIX_1, 'a', BC_INT32, 0, 0, 0, 1, BC_OBJECT_END
}).get("a"));
}

private static void assertMalformedAcrossNumberReaders(byte[] bytes) {
assertThrows(JSONException.class, () -> JSONB.parse(bytes));
assertThrows(JSONException.class, () -> JSONB.parseObject(bytes, Integer.class));
assertThrows(JSONException.class, () -> JSONB.parseObject(bytes, Long.class));
assertThrows(JSONException.class, () -> JSONB.parseObject(bytes, BigInteger.class));
assertThrows(JSONException.class, () -> JSONB.parseObject(bytes, BigDecimal.class));

assertMalformed(bytes, JSONReader::readAny);
assertMalformed(bytes, JSONReader::readInt32Value);
assertMalformed(bytes, JSONReader::readInt32);
assertMalformed(bytes, JSONReader::readInt64Value);
assertMalformed(bytes, JSONReader::readInt64);
assertMalformed(bytes, JSONReader::readNumber);
assertMalformed(bytes, JSONReader::readBigInteger);
assertMalformed(bytes, JSONReader::readBigDecimal);
assertMalformed(bytes, JSONReader::readFloatValue);
assertMalformed(bytes, JSONReader::readDoubleValue);
}

private static void assertMalformed(byte[] bytes, Function<JSONReader, ?> action) {
JSONReader reader = JSONReader.ofJSONB(bytes);
assertThrows(JSONException.class, () -> action.apply(reader));
}

private static void assertMalformedSlice(byte[] bytes) {
assertMalformedSlice(bytes, JSONReader::readAny);
}

private static void assertMalformedSlice(byte[] bytes, Function<JSONReader, ?> action) {
byte[] backing = new byte[bytes.length + 2];
System.arraycopy(bytes, 0, backing, 0, bytes.length);
backing[bytes.length] = 1;
backing[bytes.length + 1] = BC_OBJECT_END;
JSONReader reader = JSONReader.ofJSONB(backing, 0, bytes.length);
assertThrows(JSONException.class, () -> action.apply(reader));
}
}