Assembler crash via backslash counter underrun

Heap buffer overflow in quote_for_pmake in NASM before 2.16 and 2.16rc1 allows local users to crash the assembler with a crafted file. The function uses a post-decrement loop that leaves its backslash counter at -1, then reuses that value as a write count and overruns the allocated heap buffer. Exploitation requires a user to invoke NASM on attacker-controlled assembly input; the upstream report demonstrates a segmentation fault.