Memory issues with HashTable when resizing

[Mibu287]

As I read file pandas/_libs/src/klib/khash.h, I notice lines 226, 227 in macro kh_resize_##name (source)

h->keys = (khkey_t*)realloc(h->keys, new_n_buckets * sizeof(khkey_t)); \
if (kh_is_map) h->vals = (khval_t*)realloc(h->vals, new_n_buckets * sizeof(khval_t)); \

If realloc fail in either statement, it set h->keys or h->vals to NULL and leak original pointer value. Any attempt to deref new value of h->keys or h->vals will lead to undefined behaviors.

Should we assign result of memory allocation to a temporary variable and perform check before reassign to HashTable's internal data?

[jbrockmendel]

cc @WillAyd

[WillAyd]

Yea I think that makes sense. This code is vendored from klib so worth checking if it's been patched upstream first otherwise can do here.