Dr. Memory internal crash at PC 0x00007f81ffc78244

I was running Dr. Memory over some CppUTest unit test executables when the utility issued an internal crash report.

```
~~Dr.M~~ Dr. Memory version 2.0.1
.~~Dr.M~~
...
~~31259~~ #17 libpthread.so.0!start_thread
~~31259~~ #18 libc.so.6!__GI___clone [../sysdeps/unix/sysv/linux/x86_64/clone.S:95]
~~31259~~ Note: @0:02:05.174 in thread 31259
~~31259~~ Note: refers to 0 byte(s) beyond last valid byte in prior malloc
~~31259~~ Note: prev lower malloc: 0x00007f81fbcc6030-0x00007f81fbcc6042
~~31259~~ Note: instruction: pcmpistri %xmm3 (%rdi) $0x02 -> %ecx

```

It requests that I provide the crash report here so I have done so.

As requested on the Obtaining Help and Reporting Bugs page I have attempted to re-create the issue and capture the ldmp file. I started a run on the same code again with the `drmemory -dr_ops "-dumpcore_mask 0x8bff" `option but no ldmp was generated. I tried again with `-dr_ops "-dumpcore_mask 0x48bff"`.

Please let me know if there are other steps I can take to aid diagnosis.