r362067 - asm goto: fix out-of-bounds read of Constraints after rC362045

[Fangrui Song via cfe-commits]

Author: maskray
Date: Thu May 30 01:03:02 2019
New Revision: 362067

URL: http://llvm.org/viewvc/llvm-project?rev=362067&view=rev
Log:
asm goto: fix out-of-bounds read of Constraints after rC362045

When parsing goto labels, Names and Exprs are expanded but Constraints
is not, this may cause a out-of-bounds read later in:

// GCCAsmStmt::GCCAsmStmt
// `constraints` has only `NumExprs - NumLabels` elements
  Constraints = new (C) StringLiteral*[NumExprs];
  std::copy(constraints, constraints + NumExprs, Constraints);

Modified:
    cfe/trunk/lib/Parse/ParseStmtAsm.cpp

Modified: cfe/trunk/lib/Parse/ParseStmtAsm.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Parse/ParseStmtAsm.cpp?rev=362067&r1=362066&r2=362067&view=diff
==============================================================================
--- cfe/trunk/lib/Parse/ParseStmtAsm.cpp (original)
+++ cfe/trunk/lib/Parse/ParseStmtAsm.cpp Thu May 30 01:03:02 2019
@@ -846,6 +846,7 @@ StmtResult Parser::ParseAsmStatement(boo
       ExprResult Res =
           Actions.ActOnAddrLabel(Tok.getLocation(), Tok.getLocation(), LD);
       Exprs.push_back(Res.get());
+      Constraints.emplace_back();
       NumLabels++;
       ConsumeToken();
       if (!TryConsumeToken(tok::comma))