Why electric fence/Valgrind is unable to catch this buffer-overflow issue?

Question

I have created a buggy program - buggy.c - this is a buffer-overflow scenario for buffer t. You can see that I am writing more than 5 indexes. It works fine. It never throws me

Answer 1

Citing from valgrind quick start guide: "For example, it can't detect out-of-range reads or writes to arrays that are allocated statically or on the stack."