pkg/ast: fix out-of-bounds access

Scanner can access data out of bounds on bad input. Also fix regression fuzz test to be able to detect the bug.
google · Jul 30, 2019 · 3b37734 · 3b37734
1 parent 314ea0c
commit 3b37734
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Showing 2 changed files with 1 addition and 2 deletions.
diff --git a/pkg/ast/scanner.go b/pkg/ast/scanner.go
@@ -279,7 +279,6 @@ func (s *scanner) next() {
 		// Makes lots of things simpler as we always
 		// want to treat EOF as NEWLINE as well.
 		s.ch = '\n'
-		s.off++
 		return
 	}
 	if s.off > len(s.data) {

diff --git a/pkg/compiler/compiler_test.go b/pkg/compiler/compiler_test.go
@@ -202,7 +202,7 @@ type D[e]l`,
 		"E",
 		"#",
 	} {
-		Fuzz([]byte(data))
+		Fuzz([]byte(data)[:len(data):len(data)])
 	}
 }