[9] RFR (S): 8175340: Possible invalid memory accesses due to ciMethodData::bci_to_data() returning NULL

[Vladimir Kozlov]

Looks good.

thanks,
Vladimir

On 3/8/17 1:57 AM, Zoltán Majó wrote:
> Hi,
>
>
> please review the fix for 8175340.
>
> https://bugs.openjdk.java.net/browse/JDK-8175340
> http://cr.openjdk.java.net/~zmajo/8175340/webrev.01/
>
> The method ciMethodData::bci_to_data() can return NULL instead of a valid ciProfileData*. Some users of the ciProfileData returned by bci_to_data() do not check if the returned value is NULL, which
> can result in an invalid memory accesses.
>
> The issue has never happened in practice. While working on the issue, however, I experimented with a VM version that had asserts in Parse::branch_prediction and to Parse::dynamic_branch_prediction
> checking that bci_to_data() is not NULL. I was able to trigger some of the asserts I added by running the VM with -XX:-ProfileInterpreter -XX:-TieredCompilation. (The asserts are not part of the patch
> sent out for review.)
>
> The fix I propose is simple: Check if bci_to_data() is NULL, if yes, do not use profiling information / generate profiling code.
>
> The fix passes JPRT and RBT testing.
>
> Thank you!
>
> Best regards,
>
>
> Zoltan
>