Workaround a bug exposed by the FileCheckify of message-length.c, the caret end

column computation isn't correct and could exceed the line length, which
resulted in a buffer overflow later.
 - Chris, is there a better way for this code to compute the final column used
   by the caret?

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@84475 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 6 insertions, 0 deletions

diff --git a/lib/Frontend/TextDiagnosticPrinter.cpp b/lib/Frontend/TextDiagnosticPrinter.cpp
index 63d9a50b36..14769c1873 100644
--- a/lib/Frontend/TextDiagnosticPrinter.cpp
+++ b/lib/Frontend/TextDiagnosticPrinter.cpp
@@ -214,6 +214,7 @@ static void SelectInterestingSourceRegion(std::string &SourceLine,
     // Move the end of the interesting region right until we've
     // pulled in something else interesting.
     if (CaretEnd != SourceLength) {
+      assert(CaretEnd < SourceLength && "Unexpected caret position!");
       unsigned NewEnd = CaretEnd;
 
       // Skip over any whitespace we see here; we're looking for
@@ -320,6 +321,11 @@ void TextDiagnosticPrinter::EmitCaretDiagnostic(SourceLocation Loc,
   while (*LineEnd != '\n' && *LineEnd != '\r' && *LineEnd != '\0')
     ++LineEnd;
 
+  // FIXME: This shouldn't be necessary, but the CaretEndColNo can extend past
+  // the source line length as currently being computed. See
+  // test/Misc/message-length.c.
+  CaretEndColNo = std::min(CaretEndColNo, unsigned(LineEnd - LineStart));
+
   // Copy the line of code into an std::string for ease of manipulation.
   std::string SourceLine(LineStart, LineEnd);