a buffer returned from BIO_gets is not checked for it's length before
reading its contents.
Reviewed-by: NBen Kaduk <kaduk@mit.edu>
Reviewed-by: NAndy Polyakov <appro@openssl.org>
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3630)