[openssl/openssl] 4bad47: embed bio_dgram_data inside bio_dgram_sctp_data

[Neil Horman]

  Branch: refs/heads/master
  Home:   https://github.com/openssl/openssl
  Commit: 4bad474746472f08b0247b5afa81ddc71df98d5f
      https://github.com/openssl/openssl/commit/4bad474746472f08b0247b5afa81ddc71df98d5f
  Author: Neil Horman <nhorman at openssl.org>
  Date:   2023-10-05 (Thu, 05 Oct 2023)

  Changed paths:
    M crypto/bio/bss_dgram.c

  Log Message:
  -----------
  embed bio_dgram_data inside bio_dgram_sctp_data

the sctp BIO implementation uses the generic BIO dgram implementation
under the covers for some operations.  However, the private data for
each bio is incongruous, leading to segfaults when doing things like
passing a dgram_sctp_ctrl operation to the underlying dgram_ctrl method.

Fix this by removing the common fields between the two strcutres and
embedding a bio_dgram_data as the first member of the
bio_dgram_sctp_data struct.  This allows implicit casting when that call
path is taken, avoiding any memory mis-use

Fixes #20643

Reviewed-by: Matt Caswell <matt at openssl.org>
Reviewed-by: Paul Dale <pauli at openssl.org>
Reviewed-by: Tomas Mraz <tomas at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/22278)