Semmle: Fix possible infite loops caused by overflow (#3503)

Comparison between differently sized integers in loop conditions can cause
infinite loops. This can happen when doing something like this:

```c
int64 very_big = MAX_INT32 + 1;
for (int32 i = 0; i < very_big; i++) {
    // do something
}
// never reached because i overflows before it can reach the value of very_big
```

src/backend/distributed/connection/connection_configuration.c

@@ -76,7 +76,7 @@ InitConnParams()
 void
 ResetConnParams()
 {
-	for (Index paramIdx = 0; paramIdx < ConnParams.size; paramIdx++)
+	for (Size paramIdx = 0; paramIdx < ConnParams.size; paramIdx++)
 	{
 		free((void *) ConnParams.keywords[paramIdx]);
 		free((void *) ConnParams.values[paramIdx]);
@@ -135,7 +135,6 @@ CheckConninfo(const char *conninfo, const char **whitelist,
 			  Size whitelistLength, char **errorMsg)
 {
 	PQconninfoOption *option = NULL;
-	Index whitelistIdx PG_USED_FOR_ASSERTS_ONLY = 0;
 	char *errorMsgString = NULL;
 
 	/*
@@ -174,7 +173,7 @@ CheckConninfo(const char *conninfo, const char **whitelist,
 #ifdef USE_ASSERT_CHECKING
 
 	/* verify that the whitelist is in ascending order */
-	for (whitelistIdx = 1; whitelistIdx < whitelistLength; whitelistIdx++)
+	for (Size whitelistIdx = 1; whitelistIdx < whitelistLength; whitelistIdx++)
 	{
 		const char *prev = whitelist[whitelistIdx - 1];
 		const char *curr = whitelist[whitelistIdx];
@@ -290,7 +289,7 @@ GetConnParams(ConnectionHashKey *key, char ***keywords, char ***values,
 	pg_ltoa(key->port, nodePortString); /* populate node port string with port */
 
 	/* first step: copy global parameters to beginning of array */
-	for (Index paramIndex = 0; paramIndex < ConnParams.size; paramIndex++)
+	for (Size paramIndex = 0; paramIndex < ConnParams.size; paramIndex++)
 	{
 		/* copy the keyword&value pointers to the new array */
 		connKeywords[paramIndex] = ConnParams.keywords[paramIndex];
@@ -328,7 +327,7 @@ GetConnParams(ConnectionHashKey *key, char ***keywords, char ***values,
 const char *
 GetConnParam(const char *keyword)
 {
-	for (Index i = 0; i < ConnParams.size; i++)
+	for (Size i = 0; i < ConnParams.size; i++)
 	{
 		if (strcmp(keyword, ConnParams.keywords[i]) == 0)
 		{

src/backend/distributed/deparser/citus_ruleutils.c

@@ -524,7 +524,13 @@ pg_get_tablecolumnoptionsdef_string(Oid tableRelationId)
 	 */
 	TupleDesc tupleDescriptor = RelationGetDescr(relation);
 
-	for (AttrNumber attributeIndex = 0; attributeIndex < tupleDescriptor->natts;
+	if (tupleDescriptor->natts > MaxAttrNumber)
+	{
+		ereport(ERROR, (errmsg("bad number of tuple descriptor attributes")));
+	}
+
+	for (AttrNumber attributeIndex = 0;
+		 attributeIndex < (AttrNumber) tupleDescriptor->natts;
 		 attributeIndex++)
 	{
 		Form_pg_attribute attributeForm = TupleDescAttr(tupleDescriptor, attributeIndex);

src/backend/distributed/planner/recursive_planning.c

@@ -1397,7 +1397,11 @@ TransformFunctionRTE(RangeTblEntry *rangeTblEntry)
 		 *
 		 * We will iterate over Tuple Description attributes. i.e (c1 int, c2 text)
 		 */
-		for (targetColumnIndex = 0; targetColumnIndex < tupleDesc->natts;
+		if (tupleDesc->natts > MaxAttrNumber)
+		{
+			ereport(ERROR, (errmsg("bad number of tuple descriptor attributes")));
+		}
+		for (targetColumnIndex = 0; targetColumnIndex < (AttrNumber) tupleDesc->natts;
 			 targetColumnIndex++)
 		{
 			FormData_pg_attribute *attribute = TupleDescAttr(tupleDesc,

src/backend/distributed/transaction/citus_dist_stat_activity.c

@@ -611,7 +611,7 @@ LocalNodeCitusDistStat(const char *statQuery, const char *hostname, int port)
 	 */
 	oldContext = MemoryContextSwitchTo(upperContext);
 
-	for (uint32 rowIndex = 0; rowIndex < SPI_processed; rowIndex++)
+	for (uint64 rowIndex = 0; rowIndex < SPI_processed; rowIndex++)
 	{
 		TupleDesc rowDescriptor = SPI_tuptable->tupdesc;
 

src/backend/distributed/utils/acquire_lock.c

@@ -242,8 +242,6 @@ LockAcquireHelperMain(Datum main_arg)
 
 	while (ShouldAcquireLock(100))
 	{
-		int row = 0;
-
 		elog(LOG, "canceling competing backends for backend %d", backendPid);
 
 		/*
@@ -261,7 +259,7 @@ LockAcquireHelperMain(Datum main_arg)
 
 		if (spiStatus == SPI_OK_SELECT)
 		{
-			for (row = 0; row < SPI_processed; row++)
+			for (uint64 row = 0; row < SPI_processed; row++)
 			{
 				bool isnull = false;
 

src/backend/distributed/worker/worker_partition_protocol.c

@@ -936,7 +936,7 @@ FilterAndPartitionTable(const char *filterQuery,
 
 	while (SPI_processed > 0)
 	{
-		for (int rowIndex = 0; rowIndex < SPI_processed; rowIndex++)
+		for (uint64 rowIndex = 0; rowIndex < SPI_processed; rowIndex++)
 		{
 			HeapTuple row = SPI_tuptable->vals[rowIndex];
 			TupleDesc rowDescriptor = SPI_tuptable->tupdesc;