Re: Possible memory leak on getspnam / getspnam_r

[Travis Finkenauer <tmfink () juniper net>]

> On Aug 24, 2021, at 4:14 PM, Jean Diogo <j () bsd com br> wrote:
>
> Thus, although caching is mostly required for performance, maybe this
> (caching) should happen only on getspnam function but not on getspnam_r.
> That's because on getspnam_r the user wants to have control over this
> buffering, then the user has a way to clean up it's memory when this
> caching is not desired.

Per Hyrum's Law [1], there are users who expect this caching behavior. Such
users would hit a performance regression and be upset.

To control the caching behavior, there could be another function like
getspnam_r_with_cache() that takes an additional 'void **cache' parameter.
getspnam_r_with_cache() could update the pointer to point to a cache. If a user
wants to avoid caching, then the user could just pass NULL instead.

Alternatively, a new function cleanup_and_zeroize_caches() could added. A user
could call this after fork().

Of course, introducing a new function complicates the APIs and requires
developers to add them. Also, to support multiple versions of libraries,
developers would need to protect the call with an '#ifdef SUPPORTS_NEW_FUNCTION'.

-Travis

[1]: https://www.hyrumslaw.com/