stack: use free thunk when deep copy cleanup fails

stack: use free thunk when deep copy cleanup fails

internal_copy() used the generic OPENSSL_sk_freefunc directly when a deep
copy failed after copying some elements.  For typed stacks, callers pass
type-specific free callbacks that have been cast to OPENSSL_sk_freefunc, so
calling them through the generic function pointer type is undefined behavior.

Signed-off-by: Nikola Pajkovsky <nikolap@openssl.org>
Reviewed-by: Eugene Syromiatnikov <esyr@openssl.org>
Reviewed-by: Neil Horman <nhorman@openssl.org>
MergeDate: Wed May 20 15:53:43 2026
(Merged from https://github.com/openssl/openssl/pull/31151)