rtos: better sanity checking for uCOS-III

This patch improves the OSRunning check. If the rtos_running check
fails, update_threads will return an error rather than attempt to update
the thread list using bad values.

Change-Id: I8614c325504d3a9ab19aebb6862b1fe445a0c8e7
Signed-off-by: Steven Stallion <stallion@squareup.com>
Reviewed-on: http://openocd.zylin.com/4166


Tested-by: jenkins
Reviewed-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>

src/rtos/uCOS-III.c

@@ -300,6 +300,11 @@ static int uCOS_III_update_threads(struct rtos *rtos)
 		return retval;
 	}
 
+	if (rtos_running != 1 && rtos_running != 0) {
+		LOG_ERROR("uCOS-III: invalid RTOS running value");
+		return ERROR_FAIL;
+	}
+
 	if (!rtos_running) {
 		rtos->thread_details = calloc(1, sizeof(struct thread_detail));
 		if (rtos->thread_details == NULL) {