9642 PKCS#11 softtoken should use explicit_bzero
Reviewed by: Dan McDonald <danmcd@joyent.com>
Reviewed by: Alex Wilson <alex.wilson@joyent.com>

*** 20,33 ****
   * CDDL HEADER END
   */
  /*
   * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   */
  
- #pragma ident   "%Z%%M% %I%     %E% SMI"
- 
  #include <pthread.h>
  #include <sys/md5.h>
  #include <sys/sha1.h>
  #include <sys/sha2.h>
  #include <stdlib.h>
--- 20,32 ----
   * CDDL HEADER END
   */
  /*
   * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
+  * Copyright (c) 2018, Joyent, Inc.
   */
  
  #include <pthread.h>
  #include <sys/md5.h>
  #include <sys/sha1.h>
  #include <sys/sha2.h>
  #include <stdlib.h>
*** 560,575 ****
  clean_exit:
  
          (void) pthread_mutex_lock(&session_p->session_mutex);
  
          if (sign_op) {
!                 bzero(session_p->sign.context, sizeof (soft_hmac_ctx_t));
!                 free(session_p->sign.context);
                  session_p->sign.context = NULL;
          } else {
!                 bzero(session_p->verify.context, sizeof (soft_hmac_ctx_t));
!                 free(session_p->verify.context);
                  session_p->verify.context = NULL;
          }
  
          (void) pthread_mutex_unlock(&session_p->session_mutex);
  
--- 559,572 ----
  clean_exit:
  
          (void) pthread_mutex_lock(&session_p->session_mutex);
  
          if (sign_op) {
!                 freezero(session_p->sign.context, sizeof (soft_hmac_ctx_t));
                  session_p->sign.context = NULL;
          } else {
!                 freezero(session_p->verify.context, sizeof (soft_hmac_ctx_t));
                  session_p->verify.context = NULL;
          }
  
          (void) pthread_mutex_unlock(&session_p->session_mutex);