Crash report

A very large comment in heapcrpt.py causes tokenizer.c to perform an illegal write, leading to heap corruption and crashing the interpreter

Error messages

Linux/glibc: double free or corruption (!prev)
Windows: 0xc0000374 in event viewer

Your environment

Reproduced on cpython 3.10.0, 3.10.8, 3.12.0a2
Reproduced on fedora 35 (x64), windows 10 (x64, 17763.316)

Not reproduced on cpython 3.9.15
Not visibly reproduced on macos 10.13

Linked PRs

• gh-99581: Fix a buffer overflow in the tokenizer when copying lines that fill the available buffer #99605
• [3.11] gh-99581: Fix a buffer overflow in the tokenizer when copying lines that fill the available buffer (GH-99605) #99627
• [3.11] gh-99581: Fix a buffer overflow in the tokenizer when copying lines that fill the available buffer (GH-99605) #99628
• [3.10] gh-99581: Fix a buffer overflow in the tokenizer when copying lines that fill the available buffer (GH-99605). #99630