Wrap GetSplitTunnelItems and GetEnabledApps with RunOffCgoStack

Both functions allocate pointer-bearing Go types ([]string, map)
on the CGo callback stack, causing bulkBarrierPreWrite panics on
macOS when the GC tries to install write barriers on non-heap memory.

This is the same bug fixed for GetAvailableServers in #8541 and
GetAutoLocation in radiance#361. The fix is identical: run the
function body on a real Go goroutine via RunOffCgoStack.

Fixes getlantern/engineering#3088

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: myleshorton

lantern-core/core.go

@@ -943,40 +943,42 @@ func (lc *LanternCore) splitTunnelHandler() (*vpn.SplitTunnel, error) {
 }
 
 func (lc *LanternCore) GetSplitTunnelItems(filterType string) (string, error) {
-	st, err := lc.splitTunnelHandler()
-	if err != nil {
-		return "", err
-	}
+	return common.RunOffCgoStack(func() (string, error) {
+		st, err := lc.splitTunnelHandler()
+		if err != nil {
+			return "", err
+		}
 
-	f := st.Filters()
-
-	var items []string
-	switch filterType {
-	case vpn.TypeDomain:
-		items = f.Domain
-	case vpn.TypeDomainSuffix:
-		items = f.DomainSuffix
-	case vpn.TypeDomainKeyword:
-		items = f.DomainKeyword
-	case vpn.TypeDomainRegex:
-		items = f.DomainRegex
-	case vpn.TypeProcessName:
-		items = f.ProcessName
-	case vpn.TypeProcessPath:
-		items = f.ProcessPath
-	case vpn.TypeProcessPathRegex:
-		items = f.ProcessPathRegex
-	case vpn.TypePackageName:
-		items = f.PackageName
-	default:
-		return "", fmt.Errorf("unsupported filter type: %s", filterType)
-	}
+		f := st.Filters()
+
+		var items []string
+		switch filterType {
+		case vpn.TypeDomain:
+			items = f.Domain
+		case vpn.TypeDomainSuffix:
+			items = f.DomainSuffix
+		case vpn.TypeDomainKeyword:
+			items = f.DomainKeyword
+		case vpn.TypeDomainRegex:
+			items = f.DomainRegex
+		case vpn.TypeProcessName:
+			items = f.ProcessName
+		case vpn.TypeProcessPath:
+			items = f.ProcessPath
+		case vpn.TypeProcessPathRegex:
+			items = f.ProcessPathRegex
+		case vpn.TypePackageName:
+			items = f.PackageName
+		default:
+			return "", fmt.Errorf("unsupported filter type: %s", filterType)
+		}
 
-	b, err := json.Marshal(items)
-	if err != nil {
-		return "", err
-	}
-	return string(b), nil
+		b, err := json.Marshal(items)
+		if err != nil {
+			return "", err
+		}
+		return string(b), nil
+	})
 }
 
 func jsonNumberToIntString(f float64) string {
@@ -1017,67 +1019,69 @@ func (lc *LanternCore) GetAppDataDir() string {
 }
 
 func (lc *LanternCore) GetEnabledApps() (string, error) {
-	path := filepath.Join(settings.GetString(settings.DataPathKey), "split-tunnel.json")
-	b, err := os.ReadFile(path)
-	if err != nil {
-		if os.IsNotExist(err) {
+	return common.RunOffCgoStack(func() (string, error) {
+		path := filepath.Join(settings.GetString(settings.DataPathKey), "split-tunnel.json")
+		b, err := os.ReadFile(path)
+		if err != nil {
+			if os.IsNotExist(err) {
+				return "[]", nil
+			}
+			return "", err
+		}
+		if len(b) == 0 {
 			return "[]", nil
 		}
-		return "", err
-	}
-	if len(b) == 0 {
-		return "[]", nil
-	}
 
-	var m map[string]any
-	if err := json.Unmarshal(b, &m); err != nil {
-		return "", err
-	}
+		var m map[string]any
+		if err := json.Unmarshal(b, &m); err != nil {
+			return "", err
+		}
 
-	candidateKeys := []string{
-		"processPathRegex",
-		"processPath",
-		"packageName",
-		"bundleId",
-		"bundleID",
-		"enabledApps",
-		"apps",
-	}
+		candidateKeys := []string{
+			"processPathRegex",
+			"processPath",
+			"packageName",
+			"bundleId",
+			"bundleID",
+			"enabledApps",
+			"apps",
+		}
 
-	seen := map[string]struct{}{}
-	out := make([]string, 0, 16)
+		seen := map[string]struct{}{}
+		out := make([]string, 0, 16)
 
-	addList := func(v any) {
-		arr, ok := v.([]any)
-		if !ok {
-			return
-		}
-		for _, it := range arr {
-			s, ok := it.(string)
+		addList := func(v any) {
+			arr, ok := v.([]any)
 			if !ok {
-				continue
-			}
-			s = strings.TrimSpace(s)
-			if s == "" {
-				continue
+				return
 			}
-			if common.IsWindows() {
-				s = strings.ToLower(s)
+			for _, it := range arr {
+				s, ok := it.(string)
+				if !ok {
+					continue
+				}
+				s = strings.TrimSpace(s)
+				if s == "" {
+					continue
+				}
+				if common.IsWindows() {
+					s = strings.ToLower(s)
+				}
+				if _, exists := seen[s]; exists {
+					continue
+				}
+				seen[s] = struct{}{}
+				out = append(out, s)
 			}
-			if _, exists := seen[s]; exists {
-				continue
-			}
-			seen[s] = struct{}{}
-			out = append(out, s)
 		}
-	}
 
-	for _, k := range candidateKeys {
-		if v, ok := m[k]; ok {
-			addList(v)
+		for _, k := range candidateKeys {
+			if v, ok := m[k]; ok {
+				addList(v)
+			}
 		}
-	}
 
-	encoded, _ := json.Marshal(out)
-	return string(encoded), nil
+		encoded, _ := json.Marshal(out)
+		return string(encoded), nil
+	})
 }