fix: correct sloppy overflow

runtime/include/runtime.h

@@ -29,6 +29,7 @@ extern FILE *runtime_sandbox_perf_log;
  * See runtime_get_processor_speed_MHz for further details
  */
 extern uint32_t runtime_processor_speed_MHz;
+extern uint64_t runtime_relative_deadline_us_max;
 
 /* Count of worker threads and array of their pthread identifiers */
 extern pthread_t runtime_worker_threads[];

runtime/src/main.c

@@ -20,10 +20,11 @@
 /* Conditionally used by debuglog when NDEBUG is not set */
 int32_t debuglog_file_descriptor = -1;
 
-uint32_t runtime_processor_speed_MHz                          = 0;
+uint32_t runtime_processor_speed_MHz      = 0;
-uint32_t runtime_total_online_processors                      = 0;
+uint64_t runtime_relative_deadline_us_max = 0; /* a value higher than this will cause overflow on a uint64_t */
-uint32_t runtime_worker_threads_count                         = 0;
+uint32_t runtime_total_online_processors  = 0;
-uint32_t runtime_first_worker_processor                       = 0;
+uint32_t runtime_worker_threads_count     = 0;
+uint32_t runtime_first_worker_processor   = 0;
 int runtime_worker_threads_argument[WORKER_THREAD_CORE_COUNT] = { 0 }; /* The worker sets its argument to -1 on error */
 pthread_t runtime_worker_threads[WORKER_THREAD_CORE_COUNT];
 
@@ -90,7 +91,7 @@ runtime_allocate_available_cores()
 	char *worker_count_raw = getenv("SLEDGE_NWORKERS");
 	if (worker_count_raw != NULL) {
 		int worker_count = atoi(worker_count_raw);
-		if (worker_count < 0 || worker_count > max_possible_workers) {
+		if (worker_count <= 0 || worker_count > max_possible_workers) {
 			panic("Invalid Worker Count. Was %d. Must be {1..%d}\n", worker_count, max_possible_workers);
 		}
 		runtime_worker_threads_count = worker_count;
@@ -236,6 +237,7 @@ main(int argc, char **argv)
 	runtime_processor_speed_MHz = runtime_get_processor_speed_MHz();
 	if (unlikely(runtime_processor_speed_MHz == 0)) panic("Failed to detect processor speed\n");
 
+	runtime_relative_deadline_us_max               = UINT64_MAX / runtime_processor_speed_MHz;
 	software_interrupt_interval_duration_in_cycles = (uint64_t)SOFTWARE_INTERRUPT_INTERVAL_DURATION_IN_USEC
 	                                                 * runtime_processor_speed_MHz;
 	printf("Detected processor speed of %u MHz\n", runtime_processor_speed_MHz);

runtime/src/module.c

@@ -193,7 +193,12 @@ module_new(char *name, char *path, int32_t argument_count, uint32_t stack_size,
 
 	/* Deadlines */
 	module->relative_deadline_us = relative_deadline_us;
-	module->relative_deadline    = relative_deadline_us * runtime_processor_speed_MHz;
+
+	/* This should have been handled when a module was loaded */
+	assert(relative_deadline_us < runtime_relative_deadline_us_max);
+
+	/* This can overflow a uint32_t, so be sure to cast appropriately */
+	module->relative_deadline = (uint64_t)relative_deadline_us * runtime_processor_speed_MHz;
 
 	/* Admissions Control */
 	uint64_t expected_execution = expected_execution_us * runtime_processor_speed_MHz;
@@ -389,7 +394,7 @@ module_new_from_json(char *file_name)
 				is_active = (strcmp(val, "yes") == 0);
 			} else if (strcmp(key, "relative-deadline-us") == 0) {
 				unsigned long long buffer = strtoull(val, NULL, 10);
-				if (buffer > UINT32_MAX)
+				if (buffer > runtime_relative_deadline_us_max)
 					panic("Max relative-deadline-us is %u, but entry was %llu\n", UINT32_MAX,
 					      buffer);
 				relative_deadline_us = (uint32_t)buffer;