RFR: 8306461: ObjectInputStream::readObject() should handle negative array sizes without throwing NegativeArraySizeExceptions

[Volker Simonis]

On Thu, 20 Apr 2023 18:53:53 GMT, Roger Riggs <rriggs at openjdk.org> wrote:

>> This issue was reported by: Yakov Shafranovich ([yakovsh at amazon.com](mailto:yakovsh at amazon.com))
>> 
>> Currently, `ObjectInputStream::readObject()` doesn't explicitly checks for a negative array length in the deserialization stream. Instead it calls `j.l.r.Array::newInstance(..)` with the negative length which results in a `NegativeArraySizeException`. NegativeArraySizeException is an unchecked exception which is neither declared in the signature of `ObjectInputStream::readObject()` nor mentioned in its API specification. It is therefore not obvious for users of `ObjectInputStream::readObject()` that they may have to handle `NegativeArraySizeException`s. It would therefor be better if a negative array length in the deserialization stream would be automatically wrapped in an `InvalidClassException` which is a checked exception (derived from `IOException` via `ObjectStreamException`) and declared in the signature of `ObjectInputStream::readObject()`.
>> 
>> If we do the negative array length check in `ObjectInputStream::readObject()` before filtering, this will then also fix `ObjectInputFilter.FilterInfo::arrayLength()` which is defined as:
>> 
>> Returns:
>> the non-negative number of array elements when deserializing an array of the class, otherwise -1
>> 
>> but currently returns a negative value if the array length is negative.
>
> test/jdk/java/io/ObjectInputStream/NegativeArraySizeTest.java line 59:
> 
>> 57:             if (serializedData[i] == 0x78) {
>> 58:                 firstPos = i;
>> 59:                 break;
> 
> Move setting the length code (lines 64-67) here and return immediately.

Fixed.

> test/jdk/java/io/ObjectInputStream/NegativeArraySizeTest.java line 62:
> 
>> 60:             }
>> 61:         }
>> 62: 
> 
> The test should fail if it falls through without finding the BLOCKDATA. Just a double guard against the unexpected.

Fixed.

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PR Review Comment: https://git.openjdk.org/jdk/pull/13540#discussion_r1175180242
PR Review Comment: https://git.openjdk.org/jdk/pull/13540#discussion_r1175180425