[llvm] r221868 - Object, COFF: Fix some theoretical bugs

[David Majnemer]

Author: majnemer
Date: Thu Nov 13 01:42:07 2014
New Revision: 221868

URL: http://llvm.org/viewvc/llvm-project?rev=221868&view=rev
Log:
Object, COFF: Fix some theoretical bugs

getObject didn't consider the case where a pointer came before the start
of the object file.  No test is included, trying to come up with
something reasonable.

Modified:
    llvm/trunk/lib/Object/COFFObjectFile.cpp

Modified: llvm/trunk/lib/Object/COFFObjectFile.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Object/COFFObjectFile.cpp?rev=221868&r1=221867&r2=221868&view=diff
==============================================================================
--- llvm/trunk/lib/Object/COFFObjectFile.cpp (original)
+++ llvm/trunk/lib/Object/COFFObjectFile.cpp Thu Nov 13 01:42:07 2014
@@ -43,11 +43,12 @@ static bool checkSize(MemoryBufferRef M,
 // Returns unexpected_eof if error.
 template <typename T>
 static std::error_code getObject(const T *&Obj, MemoryBufferRef M,
-                                 const uint8_t *Ptr,
+                                 const void *Ptr,
                                  const size_t Size = sizeof(T)) {
   uintptr_t Addr = uintptr_t(Ptr);
   if (Addr + Size < Addr || Addr + Size < Size ||
-      Addr + Size > uintptr_t(M.getBufferEnd())) {
+      Addr + Size > uintptr_t(M.getBufferEnd()) ||
+      Addr < uintptr_t(M.getBufferStart())) {
     return object_error::unexpected_eof;
   }
   Obj = reinterpret_cast<const T *>(Addr);
@@ -424,6 +425,11 @@ relocation_iterator COFFObjectFile::sect
   } else {
     auto begin = reinterpret_cast<const coff_relocation*>(
         base() + Sec->PointerToRelocations);
+    if (Sec->hasExtendedRelocations()) {
+      // Skip the first relocation entry repurposed to store the number of
+      // relocations.
+      begin++;
+    }
     uint32_t NumReloc = getNumberOfRelocations(Sec, base());
     Ret.p = reinterpret_cast<uintptr_t>(begin + NumReloc);
   }
@@ -973,7 +979,12 @@ std::error_code COFFObjectFile::getReloc
 
 std::error_code COFFObjectFile::getRelocationOffset(DataRefImpl Rel,
                                                     uint64_t &Res) const {
-  Res = toRel(Rel)->VirtualAddress;
+  const coff_relocation *R = toRel(Rel);
+  const support::ulittle32_t *VirtualAddressPtr;
+  if (std::error_code EC =
+          getObject(VirtualAddressPtr, Data, &R->VirtualAddress))
+    return EC;
+  Res = *VirtualAddressPtr;
   return object_error::success;
 }