Don't overread the buffer when an %x escape in inline asm ends prematurely.

Tested by valgrind & Sema/asm.c.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@134404 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 0 deletions

diff --git a/lib/AST/Stmt.cpp b/lib/AST/Stmt.cpp
index 39f23fba9e..e293f324ab 100644
--- a/lib/AST/Stmt.cpp
+++ b/lib/AST/Stmt.cpp
@@ -366,6 +366,10 @@ unsigned AsmStmt::AnalyzeAsmString(llvm::SmallVectorImpl<AsmStringPiece>&Pieces,
     // Handle %x4 and %x[foo] by capturing x as the modifier character.
     char Modifier = '\0';
     if (isalpha(EscapedChar)) {
+      if (CurPtr == StrEnd) { // Premature end.
+        DiagOffs = CurPtr-StrStart-1;
+        return diag::err_asm_invalid_escape;
+      }
       Modifier = EscapedChar;
       EscapedChar = *CurPtr++;
     }