Index: llvm/trunk/include/llvm/Object/ELF.h
===================================================================
--- llvm/trunk/include/llvm/Object/ELF.h
+++ llvm/trunk/include/llvm/Object/ELF.h
@@ -225,7 +225,8 @@
     ArrayRef<Elf_Word> ShndxTable) const {
   assert(Sym->st_shndx == ELF::SHN_XINDEX);
   unsigned Index = Sym - FirstSym;
-
+  if (Index >= ShndxTable.size())
+    report_fatal_error("Invalid symbol table index");
   // The size of the table was checked in getSHNDXTable.
   return ShndxTable[Index];
 }
Index: llvm/trunk/test/Object/invalid.test
===================================================================
--- llvm/trunk/test/Object/invalid.test
+++ llvm/trunk/test/Object/invalid.test
@@ -54,3 +54,7 @@
 
 RUN: not llvm-readobj -t %p/Inputs/invalid-xindex-size.elf 2>&1 | FileCheck --check-prefix=INVALID-XINDEX-SIZE %s
 INVALID-XINDEX-SIZE: Invalid data was encountered while parsing the file.
+
+RUN: not llvm-readobj -t %p/Inputs/invalid-ext-symtab-index.elf-x86-64 2>&1 | \
+RUN:   FileCheck --check-prefix=INVALID-EXT-SYMTAB-INDEX %s
+INVALID-EXT-SYMTAB-INDEX: Invalid symbol table index