Possible NULL pointer dereference on freenect_select_subdevices??

[ycaibb]

Dear developers:
Our tool reports a NULL pointer dereference on this method freenect_select_subdevices where ctx may be NULL. It may a false positive, thank you for your confirmation.

FREENECTAPI void freenect_select_subdevices(freenect_context *ctx, freenect_device_flags subdevs)
{
	ctx->enabled_subdevices = ...; // ctx may be null
}

The method is invoked here.

static void init_thread(void)
{
	thread_running = 1;
	freenect_init(&ctx, 0); // store null to ctx.
	freenect_select_subdevices(ctx, (freenect_device_flags)(FREENECT_DEVICE_MOTOR | FREENECT_DEVICE_CAMERA));
	pthread_create(&thread, NULL, init, NULL);
}

This method store NULL to ctx on here.

FREENECTAPI int freenect_init(freenect_context **ctx, freenect_usb_context *usb_ctx)
{
	int res;

	*ctx = (freenect_context*)malloc(sizeof(freenect_context));
	if (*ctx == NULL)
		return -1;

	memset(*ctx, 0, sizeof(freenect_context));

	(*ctx)->log_level = LL_NOTICE;
	(*ctx)->enabled_subdevices = (freenect_device_flags)(FREENECT_DEVICE_MOTOR | FREENECT_DEVICE_CAMERA);
	res = fnusb_init(&(*ctx)->usb, usb_ctx);
	if (res < 0) {
		free(*ctx);
		*ctx = NULL;
	}
	return res;
}