allow for escaping unicode characters in css selectors

src/filters/cosmetic.rs

@@ -532,7 +532,7 @@ fn key_from_selector(selector: &str) -> Result<String, CosmeticFilterError> {
             beginning = location.end();
             // Unwrap is safe because there is a capture group specified in the regex
             let capture = capture.get(1).unwrap().as_str();
-            if capture.len() == 1 {
+            if capture.chars().count() == 1 {   // Check number of unicode characters rather than byte length
                 key += capture;
             } else {
                 // This u32 conversion can overflow

src/lists.rs

@@ -176,3 +176,22 @@ fn detect_filter_type(filter: &str) -> FilterType {
     // Everything else is a network filter
     FilterType::Network
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn parse_filter_failed_fuzz_1() {
+        let input = "Ѥ";
+        let result = parse_filter(input, true, true, true);
+        assert!(result.is_ok());
+    }
+
+    #[test]
+    fn parse_filter_failed_fuzz_2() {
+        assert!(parse_filter(r#"###\\\00DB \008D"#, true, true, true).is_ok());
+        assert!(parse_filter(r#"###\Û"#, true, true, true).is_ok());
+    }
+
+}