perf_jit_trampoline: mmap failure check uses wrong error value

[stratakis]

Bug report

Bug description:

In Python/perf_jit_trampoline.c, the perf_map_jit_init function checks for NULL to detect mmap failures, but mmap() returns MAP_FAILED (which is (void*)-1) on error, not NULL.

cpython/Python/perf_jit_trampoline.c

Line 1086 in 25a10b6

if (perf_jit_map_state.mapped_buffer == NULL) {

This means mmap failures are never detected, and jitdump initialization proceeds with an invalid pointer.

CPython versions tested on:

CPython main branch, 3.15, 3.14, 3.13

Operating systems tested on:

Linux

Linked PRs

• gh-144194: Fix mmap failure check in perf_jit_trampoline.c #143713