[openssl/openssl] 928893: Fix a possible use-after-free in custom_exts_free

[Bernd Edlinger]

  Branch: refs/heads/openssl-3.0
  Home:   https://github.com/openssl/openssl
  Commit: 92889328fbbb2344339f7c90afc449f6eb9b11a6
      https://github.com/openssl/openssl/commit/92889328fbbb2344339f7c90afc449f6eb9b11a6
  Author: Bernd Edlinger <bernd.edlinger at hotmail.de>
  Date:   2023-11-22 (Wed, 22 Nov 2023)

  Changed paths:
    M ssl/statem/extensions_cust.c

  Log Message:
  -----------
  Fix a possible use-after-free in custom_exts_free

This may happen when ssl_cert_dup calls custom_exts_copy, where
a possible memory allocation error causes custom_exts_free
to be called twice: once in the error handling of custom_exts_copy
and a second time in the error handling of ssl_cert_dup.

Reviewed-by: Matt Caswell <matt at openssl.org>
Reviewed-by: Tomas Mraz <tomas at openssl.org>
Reviewed-by: Richard Levitte <levitte at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/22772)

(cherry picked from commit bc0773bbbd4d3ace6957385f1f22a5cda25dc94f)