Ensure planning encodes and scans cannot infinitely recurse

#2141

Author: jackc

pgtype/json.go

@@ -130,7 +130,7 @@ func (c *JSONCodec) PlanScan(m *Map, oid uint32, format int16, target any) ScanP
 		// https://github.com/jackc/pgx/issues/1691 -- ** anything else
 
 		if wrapperPlan, nextDst, ok := TryPointerPointerScanPlan(target); ok {
-			if nextPlan := m.planScan(oid, format, nextDst); nextPlan != nil {
+			if nextPlan := m.planScan(oid, format, nextDst, 0); nextPlan != nil {
 				if _, failed := nextPlan.(*scanPlanFail); !failed {
 					wrapperPlan.SetNext(nextPlan)
 					return wrapperPlan

pgtype/pgtype.go

@@ -449,14 +449,14 @@ func (plan *scanPlanFail) Scan(src []byte, dst any) error {
 		// As a horrible hack try all types to find anything that can scan into dst.
 		for oid := range plan.m.oidToType {
 			// using planScan instead of Scan or PlanScan to avoid polluting the planned scan cache.
-			plan := plan.m.planScan(oid, plan.formatCode, dst)
+			plan := plan.m.planScan(oid, plan.formatCode, dst, 0)
 			if _, ok := plan.(*scanPlanFail); !ok {
 				return plan.Scan(src, dst)
 			}
 		}
 		for oid := range defaultMap.oidToType {
 			if _, ok := plan.m.oidToType[oid]; !ok {
-				plan := plan.m.planScan(oid, plan.formatCode, dst)
+				plan := plan.m.planScan(oid, plan.formatCode, dst, 0)
 				if _, ok := plan.(*scanPlanFail); !ok {
 					return plan.Scan(src, dst)
 				}
@@ -1064,6 +1064,14 @@ func (plan *wrapPtrArrayReflectScanPlan) Scan(src []byte, target any) error {
 
 // PlanScan prepares a plan to scan a value into target.
 func (m *Map) PlanScan(oid uint32, formatCode int16, target any) ScanPlan {
+	return m.planScanDepth(oid, formatCode, target, 0)
+}
+
+func (m *Map) planScanDepth(oid uint32, formatCode int16, target any, depth int) ScanPlan {
+	if depth > 8 {
+		return &scanPlanFail{m: m, oid: oid, formatCode: formatCode}
+	}
+
 	oidMemo := m.memoizedScanPlans[oid]
 	if oidMemo == nil {
 		oidMemo = make(map[reflect.Type][2]ScanPlan)
@@ -1073,15 +1081,15 @@ func (m *Map) PlanScan(oid uint32, formatCode int16, target any) ScanPlan {
 	typeMemo := oidMemo[targetReflectType]
 	plan := typeMemo[formatCode]
 	if plan == nil {
-		plan = m.planScan(oid, formatCode, target)
+		plan = m.planScan(oid, formatCode, target, depth)
 		typeMemo[formatCode] = plan
 		oidMemo[targetReflectType] = typeMemo
 	}
 
 	return plan
 }
 
-func (m *Map) planScan(oid uint32, formatCode int16, target any) ScanPlan {
+func (m *Map) planScan(oid uint32, formatCode int16, target any, depth int) ScanPlan {
 	if target == nil {
 		return &scanPlanFail{m: m, oid: oid, formatCode: formatCode}
 	}
@@ -1141,7 +1149,7 @@ func (m *Map) planScan(oid uint32, formatCode int16, target any) ScanPlan {
 
 	for _, f := range m.TryWrapScanPlanFuncs {
 		if wrapperPlan, nextDst, ok := f(target); ok {
-			if nextPlan := m.planScan(oid, formatCode, nextDst); nextPlan != nil {
+			if nextPlan := m.planScanDepth(oid, formatCode, nextDst, depth+1); nextPlan != nil {
 				if _, failed := nextPlan.(*scanPlanFail); !failed {
 					wrapperPlan.SetNext(nextPlan)
 					return wrapperPlan
@@ -1201,6 +1209,15 @@ func codecDecodeToTextFormat(codec Codec, m *Map, oid uint32, format int16, src
 // PlanEncode returns an Encode plan for encoding value into PostgreSQL format for oid and format. If no plan can be
 // found then nil is returned.
 func (m *Map) PlanEncode(oid uint32, format int16, value any) EncodePlan {
+	return m.planEncodeDepth(oid, format, value, 0)
+}
+
+func (m *Map) planEncodeDepth(oid uint32, format int16, value any, depth int) EncodePlan {
+	// Guard against infinite recursion.
+	if depth > 8 {
+		return nil
+	}
+
 	oidMemo := m.memoizedEncodePlans[oid]
 	if oidMemo == nil {
 		oidMemo = make(map[reflect.Type][2]EncodePlan)
@@ -1210,15 +1227,15 @@ func (m *Map) PlanEncode(oid uint32, format int16, value any) EncodePlan {
 	typeMemo := oidMemo[targetReflectType]
 	plan := typeMemo[format]
 	if plan == nil {
-		plan = m.planEncode(oid, format, value)
+		plan = m.planEncode(oid, format, value, depth)
 		typeMemo[format] = plan
 		oidMemo[targetReflectType] = typeMemo
 	}
 
 	return plan
 }
 
-func (m *Map) planEncode(oid uint32, format int16, value any) EncodePlan {
+func (m *Map) planEncode(oid uint32, format int16, value any, depth int) EncodePlan {
 	if format == TextFormatCode {
 		switch value.(type) {
 		case string:
@@ -1249,7 +1266,7 @@ func (m *Map) planEncode(oid uint32, format int16, value any) EncodePlan {
 
 	for _, f := range m.TryWrapEncodePlanFuncs {
 		if wrapperPlan, nextValue, ok := f(value); ok {
-			if nextPlan := m.PlanEncode(oid, format, nextValue); nextPlan != nil {
+			if nextPlan := m.planEncodeDepth(oid, format, nextValue, depth+1); nextPlan != nil {
 				wrapperPlan.SetNext(nextPlan)
 				return wrapperPlan
 			}

pgtype/xml.go

@@ -113,7 +113,7 @@ func (c *XMLCodec) PlanScan(m *Map, oid uint32, format int16, target any) ScanPl
 		// https://github.com/jackc/pgx/issues/1691 -- ** anything else
 
 		if wrapperPlan, nextDst, ok := TryPointerPointerScanPlan(target); ok {
-			if nextPlan := m.planScan(oid, format, nextDst); nextPlan != nil {
+			if nextPlan := m.planScan(oid, format, nextDst, 0); nextPlan != nil {
 				if _, failed := nextPlan.(*scanPlanFail); !failed {
 					wrapperPlan.SetNext(nextPlan)
 					return wrapperPlan