Bug#25203 Mysql crashes when mysql_kill() is executed in a connection using SSL

 - It's too early to free the SSL object in 'vio_ssl_close'. There
   might still be a thread using or reading from it on platforms
   where we need to close the active connection/socket in order
   to break the read.  
 - Add new function 'vio_ssl_delete' and install it as the viodelete
   function for SSL connections.


vio/vio.c:
  Install 'vio_ssl_delete' as viodelete function for SSL connections
  Cleanup 'vio_delete'
vio/vio_priv.h:
  Add declaration of vio_ssl_delete
vio/viossl.c:
  Add new function 'vio_ssl_delete' that takes care of freeing the memory
  allocated by the SSL connection
  Move the code to free the SSL object from vio_ssl_close

vio/vio.c

@@ -86,7 +86,7 @@ static void vio_init(Vio* vio, enum enum_vio_type type,
 #ifdef HAVE_OPENSSL 
   if (type == VIO_TYPE_SSL)
   {
-    vio->viodelete	=vio_delete;
+    vio->viodelete	=vio_ssl_delete;
     vio->vioerrno	=vio_errno;
     vio->read		=vio_ssl_read;
     vio->write		=vio_ssl_write;
@@ -220,17 +220,16 @@ Vio *vio_new_win32shared_memory(NET *net,HANDLE handle_file_map, HANDLE handle_m
 #endif
 #endif
 
+
 void vio_delete(Vio* vio)
 {
-  /* It must be safe to delete null pointers. */
-  /* This matches the semantics of C++'s delete operator. */
-  if (vio)
-  {
+  if (!vio)
+    return; /* It must be safe to delete null pointers. */
+
   if (vio->type != VIO_CLOSED)
     vio->vioclose(vio);
   my_free((gptr) vio->read_buffer, MYF(MY_ALLOW_ZERO_PTR));
   my_free((gptr) vio,MYF(0));
-  }
 }
 
 

vio/vio_priv.h

@@ -32,6 +32,7 @@ int	vio_ssl_write(Vio *vio,const gptr buf,int size);
 
 /* When the workday is over... */
 int vio_ssl_close(Vio *vio);
+void vio_ssl_delete(Vio *vio);
 
 int vio_ssl_blocking(Vio *vio, my_bool set_blocking_mode, my_bool *old_mode);
 

vio/viossl.c

@@ -140,13 +140,29 @@ int vio_ssl_close(Vio *vio)
                                SSL_get_error(ssl, r)));
       break;
     }
-    SSL_free(ssl);
-    vio->ssl_arg= 0;
   }
   DBUG_RETURN(vio_close(vio));
 }
 
 
+void vio_ssl_delete(Vio *vio)
+{
+  if (!vio)
+    return; /* It must be safe to delete null pointer */
+
+  if (vio->type == VIO_TYPE_SSL)
+    vio_ssl_close(vio); /* Still open, close connection first */
+
+  if (vio->ssl_arg)
+  {
+    SSL_free((SSL*) vio->ssl_arg);
+    vio->ssl_arg= 0;
+  }
+
+  vio_delete(vio);
+}
+
+
 int sslaccept(struct st_VioSSLFd *ptr, Vio *vio, long timeout)
 {
   SSL *ssl;