RFR(XS) 8129897: Old verifier fails to reject erroneous cast from boolean to byte
david.holmes at oracle.com
Thu Jul 23 01:32:15 UTC 2015
On 23/07/2015 1:06 AM, harold seigel wrote:
> Hi David,
> Thanks for the review!
> I updated lines 2256- 2261 in a new webrev:
> Here are the new lines:
> 2256 case 'B': /* array of bytes or booleans */
> 2257 if (top_type != MAKE_FULLINFO(ITEM_Byte, 1,
> 0) &&
> 2258 top_type != MAKE_FULLINFO(ITEM_Boolean,
> 1, 0))
> 2259 CCerror(context,
> 2260 "Expecting to find array of bytes
> or Booleans on stack");
> 2261 break;
> File jdk/src/java.base/share/native/libverify/opcodes.in_out defines the
> first operand for opcodes baload and bastore as [B. But, according to
> the JVM Spec, the first operand for these bytecodes can be either [B or
> [Z. This code checks that the opcodes, that opcodes.in_out says expect
> [B, do not throw VerifyError if their actual operand is either [B or
> [Z. Opcodes baload and bastore are the only opcodes in opcodes.in_out
> with [B operands, and that's unlikely to change.
> I removed "case 'Z': because there are no [Z operands for any opcodes in
Yeah they were too miserly to give booleans their own bytecodes :)
Thanks for clarifying and changing.
> Thanks, Harold
> On 7/21/2015 7:44 PM, David Holmes wrote:
>> Hi Harold,
>> On 22/07/2015 6:21 AM, harold seigel wrote:
>>> Please review this small change to fix bug 8129897. The old verifier
>>> treats arrays of Booleans as arrays of bytes, allowing assignability
>>> between them. This fix distinguishes between arrays of Booleans and
>>> arrays of bytes and so disallows assignability between them. Additional
>>> changes were needed to make sure operands to baload and similar opcodes
>>> could still be either Boolean or byte arrays.
>>> Open webrev: http://cr.openjdk.java.net/~hseigel/bug_8129897/
>> Seems reasonable. Only query I have was why you didn't split this:
>> 2256 case 'B': case 'Z': /* array of bytes or
>> booleans */
>> 2257 if (top_type != MAKE_FULLINFO(ITEM_Byte,
>> 1, 0) &&
>> 2258 top_type !=
>> MAKE_FULLINFO(ITEM_Boolean, 1, 0))
>> 2259 CCerror(context,
>> 2260 "Expecting to find array of
>> bytes or Booleans on stack");
>> 2261 break;
>> into two distinct cases?
>>> JBS Bug: https://bugs.openjdk.java.net/browse/JDK-8129897
>>> The fix was tested with JCK Lang and VM tests, the UTE quick and split
>>> verifier tests, and the hotspot, and JDK vm, java/io, java/lang, and
>>> java/util JTreg tests.
>>> This scenario will be tested by JCK-9. So no regression test was
>>> included in this webrev.
>>> Thanks, Harold
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