syntax: fix overflow for big counted repetitions

regex-syntax/src/hir/mod.rs

@@ -2481,16 +2481,24 @@ impl Properties {
  props.literal = props.literal && p.is_literal();
  props.alternation_literal =
  props.alternation_literal && p.is_alternation_literal();
- if let Some(ref mut minimum_len) = props.minimum_len {
+ if let Some(minimum_len) = props.minimum_len {
  match p.minimum_len() {
  None => props.minimum_len = None,
- Some(len) => *minimum_len += len,
+ Some(len) => {
+ // We use saturating arithmetic here because the
+ // minimum is just a lower bound. We can't go any
+ // higher than what our number types permit.
+ props.minimum_len =
+ Some(minimum_len.saturating_add(len));
+ }
  }
  }
- if let Some(ref mut maximum_len) = props.maximum_len {
+ if let Some(maximum_len) = props.maximum_len {
  match p.maximum_len() {
  None => props.maximum_len = None,
- Some(len) => *maximum_len += len,
+ Some(len) => {
+ props.maximum_len = maximum_len.checked_add(len)
+ }
  }
  }
  }

tests/regression.rs

@@ -240,3 +240,11 @@ fn regression_unicode_perl_not_enabled() {
  let re = regex_new!(pat);
  assert!(re.is_ok());
 }
+
+// See: https://github.com/rust-lang/regex/issues/995
+#[test]
+fn regression_big_regex_overflow() {
+ let pat = r" {2147483516}{2147483416}{5}";
+ let re = regex_new!(pat);
+ assert!(re.is_err());
+}