From: Alexey Bataev <a.bataev@hotmail.com>
Date: Thu, 4 Feb 2016 04:22:09 +0000 (+0000)
Subject: PR23057: fix use-after-free due to local token buffer in ParseCXXAmbiguousParenExpres... 
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=2fa0d3e203ac0ac3db8422a3db3e6e91747e3033;p=clang

PR23057: fix use-after-free due to local token buffer in ParseCXXAmbiguousParenExpression, by Dmitry Polukhin
Differential Revision: http://reviews.llvm.org/D16572
A    test/Parser/cxx-ambig-paren-expr-asan.cpp
M    lib/Parse/ParseExprCXX.cpp


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@259750 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Parse/ParseExprCXX.cpp b/lib/Parse/ParseExprCXX.cpp
index 53009caf8c..760c30b812 100644
--- a/lib/Parse/ParseExprCXX.cpp
+++ b/lib/Parse/ParseExprCXX.cpp
@@ -3081,6 +3081,14 @@ Parser::ParseCXXAmbiguousParenExpression(ParenParseOption &ExprType,
     ParseAs = NotCastExpr ? SimpleExpr : CastExpr;
   }
 
+  // Create a fake EOF to mark end of Toks buffer.
+  Token AttrEnd;
+  AttrEnd.startToken();
+  AttrEnd.setKind(tok::eof);
+  AttrEnd.setLocation(Tok.getLocation());
+  AttrEnd.setEofData(Toks.data());
+  Toks.push_back(AttrEnd);
+
   // The current token should go after the cached tokens.
   Toks.push_back(Tok);
   // Re-enter the stored parenthesized tokens into the token stream, so we may
@@ -3105,6 +3113,10 @@ Parser::ParseCXXAmbiguousParenExpression(ParenParseOption &ExprType,
     Tracker.consumeClose();
     ColonProt.restore();
 
+    // Consume EOF marker for Toks buffer.
+    assert(Tok.is(tok::eof) && Tok.getEofData() == AttrEnd.getEofData());
+    ConsumeAnyToken();
+
     if (ParseAs == CompoundLiteral) {
       ExprType = CompoundLiteral;
       if (DeclaratorInfo.isInvalidType())
@@ -3141,10 +3153,16 @@ Parser::ParseCXXAmbiguousParenExpression(ParenParseOption &ExprType,
 
   // Match the ')'.
   if (Result.isInvalid()) {
-    SkipUntil(tok::r_paren, StopAtSemi);
+    while (Tok.isNot(tok::eof))
+      ConsumeAnyToken();
+    assert(Tok.getEofData() == AttrEnd.getEofData());
+    ConsumeAnyToken();
     return ExprError();
   }
 
   Tracker.consumeClose();
+  // Consume EOF marker for Toks buffer.
+  assert(Tok.is(tok::eof) && Tok.getEofData() == AttrEnd.getEofData());
+  ConsumeAnyToken();
   return Result;
 }
diff --git a/test/Parser/cxx-ambig-paren-expr-asan.cpp b/test/Parser/cxx-ambig-paren-expr-asan.cpp
new file mode 100644
index 0000000000..ec9d6b9da3
--- /dev/null
+++ b/test/Parser/cxx-ambig-paren-expr-asan.cpp
@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 -fsyntax-only -pedantic -verify %s
+
+// This syntax error used to cause use-after free due to token local buffer
+// in ParseCXXAmbiguousParenExpression.
+int H((int()[)]);
+// expected-error@-1 {{expected expression}}
+// expected-error@-2 {{expected ']'}}
+// expected-note@-3 {{to match this '['}}
+// expected-error@-4 {{expected ';' after top level declarator}}