gh-121460: Skip freeing unallocated arenas (gh-121491)

`munmap(NULL)` is not noop, like `free(NULL)` is. Fixes an observed testsuite hang on 32-bit ARM systems. (cherry picked from commit a802277) Co-authored-by: Stefano Rivera <[email protected]>
python · Jul 10, 2024 · ef66779 · ef66779
1 parent 0113c56
commit ef66779
Showing 1 changed file with 8 additions and 0 deletions.
diff --git a/Objects/obmalloc.c b/Objects/obmalloc.c
@@ -386,8 +386,16 @@ _PyMem_ArenaFree(void *Py_UNUSED(ctx), void *ptr,
 )
 {
 #ifdef MS_WINDOWS
+    /* Unlike free(), VirtualFree() does not special-case NULL to noop. */
+    if (ptr == NULL) {
+        return;
+    }
     VirtualFree(ptr, 0, MEM_RELEASE);
 #elif defined(ARENAS_USE_MMAP)
+    /* Unlike free(), munmap() does not special-case NULL to noop. */
+    if (ptr == NULL) {
+        return;
+    }
     munmap(ptr, size);
 #else
     free(ptr);