I can reproduce the first error on linux/amd64.
It doesn't seem to fail with 1.13.
Presumably this is a bug in the tsan C++ library. It looks like a memory overwrite. The code is checking that the header of the memory block has not been clobbered between allocation and free, and it has been clobbered.
I don't see anything in the tsan tracker that might be a fix for this, after we forked it at 810ae8ddac890a6613d814c0b5415c7fcb7f5cca. But I'm not sure about that.