fixup! fixup! Secure array slicing when expanding macro for stack trace

crystal-lang · Aug 23, 2021 · 83f5096 · 83f5096
1 parent a7d30df
commit 83f5096
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/src/compiler/crystal/exception.cr b/src/compiler/crystal/exception.cr
@@ -253,8 +253,8 @@ module Crystal
         source, _ = minimize_indentation(source.lines)
         io << Crystal.with_line_numbers(source, line_number, @color)
       else
-        from_index = {0, line_number - MACRO_LINES_TO_SHOW}.max
-        to_index = {source.lines.size, line_number}.max
+        to_index = line_number.clamp(0..source.lines.size)
+        from_index = {0, to_index - MACRO_LINES_TO_SHOW}.max
         source_slice = source.lines[from_index...to_index]
         source_slice, spaces_removed = minimize_indentation(source_slice)