[11] RFR(XS): 8197828: Null pointer dereference in MultiNode::proj_out_or_null

[Vladimir Kozlov]

On 2/13/18 11:22 AM, dean.long at oracle.com wrote:
> On 2/13/18 10:37 AM, Tobias Hartmann wrote:
> 
>> Hi Vladimir,
>>
>> On 13.02.2018 18:47, Vladimir Kozlov wrote:
>>> I think we should do realtime check for NULL and use this->in(0) (allocation's control edge) if Initialize node is
>>> missing which could happen.
>> Right, we should do that:
>> http://cr.openjdk.java.net/~thartmann/8197828/webrev.01/
> 
> How would we test that it works correctly?  I don't think we ever see a missing Initialize node here, otherwise we would 
> have seen crashes.

I did see missing Initialize node when I worked on EA. Zero size array. We may not hit it in this code path because it 
is guarded by several conditions.

For example ClearArrayNode::step_through() has such check:

http://hg.openjdk.java.net/jdk/hs/file/be873d8c0114/src/hotspot/share/opto/memnode.cpp#l2813

and PhaseMacroExpand::expand_allocate_array()

http://hg.openjdk.java.net/jdk/hs/file/be873d8c0114/src/hotspot/share/opto/macro.cpp#l2022

Vladimir

> 
> dl
> 
>> Thanks,
>> Tobias
>