tools: address possible non-null terminated filenames

If a filename is a multiple of 18 characters, there will be no null-terminator.
This will result in an invalid access by the constructed StringRef.  Add a test
case to exercise this and fix that handling.  Address this same vulnerability in
llvm-readobj as well.

llvm-svn: 206145

1 files changed, 4 insertions, 1 deletions

diff --git a/llvm/tools/llvm-readobj/COFFDumper.cpp b/llvm/tools/llvm-readobj/COFFDumper.cpp
index 69be82ec3e7..8d08d021a38 100644
--- a/llvm/tools/llvm-readobj/COFFDumper.cpp
+++ b/llvm/tools/llvm-readobj/COFFDumper.cpp
@@ -977,7 +977,10 @@ void COFFDumper::printSymbol(const SymbolRef &Sym) {
         break;
 
       DictScope AS(W, "AuxFileRecord");
-      W.printString("FileName", StringRef(Aux->FileName));
+
+      StringRef Name(Aux->FileName,
+                     Symbol->NumberOfAuxSymbols * COFF::SymbolSize);
+      W.printString("FileName", Name.rtrim(StringRef("\0", 1)));
     } else if (Symbol->isSectionDefinition()) {
       const coff_aux_section_definition *Aux;
       if (error(getSymbolAuxData(Obj, Symbol + I, Aux)))