Add timezone validation

Signed-off-by: Dmitry Rubtsov <me@mazy.wtf>

Author: mazzz1y

pkg/limayaml/defaults.go

@@ -20,6 +20,7 @@ import (
 	"strings"
 	"sync"
 	"text/template"
+	"time"
 
 	"github.com/coreos/go-semver/semver"
 	"github.com/docker/go-units"
@@ -137,21 +138,22 @@ func MACAddress(uniqueID string) string {
 
 func hostTimeZone() string {
 	// WSL2 will automatically set the timezone
-	if runtime.GOOS != "windows" {
-		tz, err := os.ReadFile("/etc/timezone")
-		if err == nil {
-			return strings.TrimSpace(string(tz))
-		}
-		zoneinfoFile, err := filepath.EvalSymlinks("/etc/localtime")
-		if err == nil {
-			for baseDir := filepath.Dir(zoneinfoFile); baseDir != "/"; baseDir = filepath.Dir(baseDir) {
-				if _, err = os.Stat(filepath.Join(baseDir, "Etc/UTC")); err == nil {
-					return strings.TrimPrefix(zoneinfoFile, baseDir+"/")
-				}
-			}
-			logrus.Warnf("could not locate zoneinfo directory from %q", zoneinfoFile)
+	if runtime.GOOS == "windows" {
+		return ""
+	}
+
+	if tzBytes, err := os.ReadFile("/etc/timezone"); err == nil {
+		if tz := strings.TrimSpace(string(tzBytes)); isValidTimezone(tz) {
+			return tz
 		}
 	}
+
+	if zoneinfoFile, err := filepath.EvalSymlinks("/etc/localtime"); err == nil {
+		if tz := extractTimezoneFromPath(zoneinfoFile); isValidTimezone(tz) {
+			return tz
+		}
+	}
+
 	return ""
 }
 
@@ -1309,3 +1311,27 @@ func unique(s []string) []string {
 	}
 	return list
 }
+
+func isValidTimezone(tz string) bool {
+	if tz == "" {
+		return false
+	}
+	_, err := time.LoadLocation(tz)
+	if err != nil {
+		if len(tz) > 30 {
+			tz = tz[:30] + "..."
+		}
+		logrus.Warnf("invalid timezone %q", tz)
+		return false
+	}
+	return true
+}
+
+func extractTimezoneFromPath(zoneinfoFile string) string {
+	for baseDir := filepath.Dir(zoneinfoFile); baseDir != "/"; baseDir = filepath.Dir(baseDir) {
+		if _, err := os.Stat(filepath.Join(baseDir, "Etc/UTC")); err == nil {
+			return strings.TrimPrefix(zoneinfoFile, baseDir+string(os.PathSeparator))
+		}
+	}
+	return ""
+}