[clang] 8826cd5 - [AST] Construct Capture objects before use

[Vitaly Buka via cfe-commits]

Author: Vitaly Buka
Date: 2023-05-24T17:09:45-07:00
New Revision: 8826cd57825d829121ad7fb73fab0a6cf30f29f6

URL: https://github.com/llvm/llvm-project/commit/8826cd57825d829121ad7fb73fab0a6cf30f29f6
DIFF: https://github.com/llvm/llvm-project/commit/8826cd57825d829121ad7fb73fab0a6cf30f29f6.diff

LOG: [AST] Construct Capture objects before use

Msan reports https://reviews.llvm.org/P8308
The reason is if PointerIntPair is not properly
constructed, setPointer uses Info::updatePointer
on uninitialized value.

Reviewed By: #clang, rsmith

Differential Revision: https://reviews.llvm.org/D150504

Added: 
    

Modified: 
    clang/include/clang/AST/Stmt.h
    clang/lib/AST/Stmt.cpp

Removed: 
    


################################################################################
diff  --git a/clang/include/clang/AST/Stmt.h b/clang/include/clang/AST/Stmt.h
index e466aa1755daf..7e72e44f178a9 100644
--- a/clang/include/clang/AST/Stmt.h
+++ b/clang/include/clang/AST/Stmt.h
@@ -3587,8 +3587,11 @@ class CapturedStmt : public Stmt {
     llvm::PointerIntPair<VarDecl *, 2, VariableCaptureKind> VarAndKind;
     SourceLocation Loc;
 
+    Capture() = default;
+
   public:
     friend class ASTStmtReader;
+    friend class CapturedStmt;
 
     /// Create a new capture.
     ///

diff  --git a/clang/lib/AST/Stmt.cpp b/clang/lib/AST/Stmt.cpp
index 8744bba6c6d9d..c31fb48a2addf 100644
--- a/clang/lib/AST/Stmt.cpp
+++ b/clang/lib/AST/Stmt.cpp
@@ -1345,6 +1345,11 @@ CapturedStmt::CapturedStmt(EmptyShell Empty, unsigned NumCaptures)
   : Stmt(CapturedStmtClass, Empty), NumCaptures(NumCaptures),
     CapDeclAndKind(nullptr, CR_Default) {
   getStoredStmts()[NumCaptures] = nullptr;
+
+  // Construct default capture objects.
+  Capture *Buffer = getStoredCaptures();
+  for (unsigned I = 0, N = NumCaptures; I != N; ++I)
+    new (Buffer++) Capture();
 }
 
 CapturedStmt *CapturedStmt::Create(const ASTContext &Context, Stmt *S,