security: add missing NULL checks and fix error handling in modules

module-access: add NULL check after pw_properties_new for
socket_access.

module-pulse-tunnel: add NULL check after 4MB calloc for ring
buffer.

module-rt: add NULL check after calloc in thread create.

module-rtp-session: add goto error after failed
pw_net_parse_address instead of falling through.

module-snapcast-discover: fix missing null-termination on
network-received data before logging it as a string.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/modules/module-rt.c

@@ -741,6 +741,8 @@ static struct spa_thread *impl_create(void *object, const struct spa_dict *props
 	struct spa_thread *thread;
 
 	this = calloc(1, sizeof(*this));
+	if (this == NULL)
+		return NULL;
 	this->impl = impl;
 	this->start = start_routine;
 	this->arg = arg;