[Bug] Possible SIGSEGV in ASSERT block of InterpreterRuntime::resolve_ldc

[Boris Ulasevich]

Hi Christoph,

Thanks for working on this. Here is the bug report:
https://bugs.openjdk.java.net/browse/JDK-8230797

regards,
Boris

On 10.09.2019 13:30, christoph.goettschkes at microdoc.com wrote:
> Hello,
> 
> I found a problem in an ASSERT block in the interpreter runtime of the template
> interpreter. Could someone please create a bug report for me and help me with
> the webrev? I will send a patch as soon as there is a bug report and the tests
> are done. Description follows below.
> 
> Thanks,
> Christoph
> 
> The runtime implementation of the ldc bytecodes has an ASSERT block, which does
> some sanity checks after the constant has been resolved [1]. The checks include
> loading the cached reference of the loaded constant using the
> ConstantPool::cp_to_object_index() method. This can fail, if the type of the
> loaded constant is not a reference, but a primitive type. This can happen on
> 32-bit ARM softfp, since double constants are loaded using the runtime
> implementation on that platform (see [2]). If no other constants have been
> loaded before and there are no cached references, using the
> ConstantPool::cp_to_object_index() method crashes HotSpot with a SIGSEGV.
> This is the backtrace of a slowdebug build:
> 
> #0  0x762f8886 in Array<unsigned short>::length (this=0x0) at src/hotspot/share/oops/array.hpp:106
> #1  0x764a1e48 in Array<unsigned short>::index_of (this=0x0, x=@0x761bc9ee: 2) at src/hotspot/share/oops/array.hpp:111
> #2  0x764a1b16 in Array<unsigned short>::find (this=0x0, x=@0x761bc9ee: 2) at src/hotspot/share/oops/array.hpp:123
> #3  0x7649a7d8 in ConstantPool::cp_to_object_index (this=0x647df840, cp_index=2) at src/hotspot/share/oops/constantPool.cpp:418
> #4  0x765e53e6 in InterpreterRuntime::resolve_ldc (thread=0x76017400, bytecode=Bytecodes::_ldc2_w) at src/hotspot/share/interpreter/interpreterRuntime.cpp:205
> #5  0x73e5c804 in ?? ()
> 
> Sample application:
> 
> class Test {
>      public static void main(String... args) {
>          double x = 4.2;
>      }
> }
> 
> [1] http://hg.openjdk.java.net/jdk/jdk/file/3fee0e6b54f5/src/hotspot/share/interpreter/interpreterRuntime.cpp#l199
> [2] http://hg.openjdk.java.net/jdk/jdk/file/3fee0e6b54f5/src/hotspot/cpu/arm/templateTable_arm.cpp#l475
>