From: Fangrui Song <maskray@google.com>
Date: Thu, 30 May 2019 08:03:02 +0000 (+0000)
Subject: asm goto: fix out-of-bounds read of Constraints after rC362045
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=a250e2cd858f79dfedeac06dde0408d49d37eed5;p=clang

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);

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@362067 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Parse/ParseStmtAsm.cpp b/lib/Parse/ParseStmtAsm.cpp
index 75f3ac396e..e1c48da5f2 100644
--- a/lib/Parse/ParseStmtAsm.cpp
+++ b/lib/Parse/ParseStmtAsm.cpp
@@ -846,6 +846,7 @@ StmtResult Parser::ParseAsmStatement(bool &msAsm) {
       ExprResult Res =
           Actions.ActOnAddrLabel(Tok.getLocation(), Tok.getLocation(), LD);
       Exprs.push_back(Res.get());
+      Constraints.emplace_back();
       NumLabels++;
       ConsumeToken();
       if (!TryConsumeToken(tok::comma))