[COFFObjectFile] Ignore broken symbol table

When binaries are compressed by UPX, information about symbol table
offset and symbol count remain unchanged (but became invalid due to
compression).
This causes failure in the constructor and the rest of the binary cannot
be processed.

Instead, reset symbol related information (symbol/string table pointers,
sizes) - this should disable the related iterators and functions while
the rest of the binary can still be processed.

Patch by Bandzi Michal!

llvm-svn: 280147

diff --git a/llvm/include/llvm/Object/COFF.h b/llvm/include/llvm/Object/COFF.h
index c563747..e2b6bee 100644 (file)
--- a/llvm/include/llvm/Object/COFF.h
+++ b/llvm/include/llvm/Object/COFF.h
@@ -699,13 +699,18 @@ public:
       return COFFBigObjHeader->PointerToSymbolTable;
     llvm_unreachable("no COFF header!");
   }
-  uint32_t getNumberOfSymbols() const {
+  uint32_t getRawNumberOfSymbols() const {
     if (COFFHeader)
       return COFFHeader->isImportLibrary() ? 0 : COFFHeader->NumberOfSymbols;
     if (COFFBigObjHeader)
       return COFFBigObjHeader->NumberOfSymbols;
     llvm_unreachable("no COFF header!");
   }
+  uint32_t getNumberOfSymbols() const {
+    if (!SymbolTable16 && !SymbolTable32)
+      return 0;
+    return getRawNumberOfSymbols();
+  }
 protected:
   void moveSymbolNext(DataRefImpl &Symb) const override;
   Expected<StringRef> getSymbolName(DataRefImpl Symb) const override;

diff --git a/llvm/lib/Object/COFFObjectFile.cpp b/llvm/lib/Object/COFFObjectFile.cpp
index a9a8107..601a7fa 100644 (file)
--- a/llvm/lib/Object/COFFObjectFile.cpp
+++ b/llvm/lib/Object/COFFObjectFile.cpp
@@ -729,8 +729,12 @@ COFFObjectFile::COFFObjectFile(MemoryBufferRef Object, std::error_code &EC)
 
   // Initialize the pointer to the symbol table.
   if (getPointerToSymbolTable() != 0) {
-    if ((EC = initSymbolTablePtr()))
-      return;
+    if ((EC = initSymbolTablePtr())) {
+      SymbolTable16 = nullptr;
+      SymbolTable32 = nullptr;
+      StringTable = nullptr;
+      StringTableSize = 0;
+    }
   } else {
     // We had better not have any symbols if we don't have a symbol table.
     if (getNumberOfSymbols() != 0) {