This fixes a crash in IE8 with ChromeFrame when a new tab was created. ...

chrome_frame/vtable_patch_manager.cc

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome_frame/vtable_patch_manager.h"
 
 #include "base/logging.h"
 
 #include "chrome_frame/function_stub.h"
 
@@ skipping 12 matching lines @@
   // Do some sanity checking of the input arguments.
   if (NULL == unknown || NULL == patches) {
     NOTREACHED();
     return E_INVALIDARG;
   }
 
   Vtable vtable = GetIFVTable(unknown);
   DCHECK(vtable);
 
   for (MethodPatchInfo* it = patches; it->index_ != -1; ++it) {
+    if (it->stub_ != NULL) {
+      // If this DCHECK fires it means that we are using the same VTable
+      // information to patch two different interfaces.
+      DCHECK(false);
+      DLOG(ERROR) << "Attempting to patch two different VTables with the "
+                  << "same VTable information";
+      continue;
+    }
+
     PROC original_fn = vtable[it->index_];
     FunctionStub* stub = FunctionStub::FromCode(original_fn);
     if (stub != NULL) {
       DLOG(ERROR) << "attempt to patch a function that's already patched";
       DCHECK(stub->absolute_target() ==
              reinterpret_cast<uintptr_t>(it->method_)) <<
              "patching the same method multiple times with different hooks?";
       continue;
     }
 
@@ skipping 15 matching lines @@
       }
     }
   }
 
   return S_OK;
 }
 
 HRESULT UnpatchInterfaceMethods(MethodPatchInfo* patches) {
   for (MethodPatchInfo* it = patches; it->index_ != -1; ++it) {
     if (it->stub_) {
-      DCHECK(it->stub_->absolute_target() == 
+      DCHECK(it->stub_->absolute_target() ==
           reinterpret_cast<uintptr_t>(it->method_));
       // Modify the stub to just jump directly to the original function.
       it->stub_->BypassStub(reinterpret_cast<void*>(it->stub_->argument()));
       it->stub_ = NULL;
       // Leave the stub in memory so that we won't break any possible chains.
     } else {
       DLOG(WARNING) << "attempt to unpatch a function that wasn't patched";
     }
   }
 
   return S_OK;
 }
 
 }  // namespace vtable_patch