Error on select Certificate

[valdeircaires]

Error message on select X509Certificate2 in RequestHandler interface

        protected override bool OnSelectClientCertificate(IWebBrowser chromiumWebBrowser, IBrowser browser, bool isProxy, string host, int port, X509Certificate2Collection certificates, ISelectClientCertificateCallback callback)
        {
            var control = (Control)chromiumWebBrowser;
            
            control.InvokeOnUiThreadIfRequired(delegate ()
            {
                var store = new X509Store(StoreName.My, StoreLocation.CurrentUser);
                store.Open(OpenFlags.OpenExistingOnly | OpenFlags.ReadOnly);
                X509Certificate2 selectedCertificate = null;
                foreach (var cert in store.Certificates)
                {
                    if (cert.SerialNumber.ToLower() == "386b18050760703f")
                    {
                        selectedCertificate = cert;
                        break;
                    }
                }
                store.Close();

                callback.Select(selectedCertificate);
                
            });
        
            return true;
        }

The error trigger in callback.Select(selectedCertificate);

System.AccessViolationException: 'Attempted to read or write to protected memory. This is usually an indication that another memory is damaged. '

[amaitland]

Basically this looks like issue #2948 which I've reopened.

I don't have any infrastructure setup for testing this so not sure exactly what's going on. If you are up for debugging then let me know and I'll provide a few pointers on where to add breakpoints.

[valdeircaires]

Using a sample available on github, the exception happens in the xmemory class at this point in the image.
The code is in C ++ and I'm not used to it

Details of exception

System.Reflection.TargetInvocationException
  HResult=0x80131604
  Message=Uma exceção foi acionada pelo destino de uma chamada.
  Source=mscorlib
  StackTrace:
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)
   at System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments)
   at System.Delegate.DynamicInvokeImpl(Object[] args)
   at System.Windows.Forms.Control.InvokeMarshaledCallbackDo(ThreadMethodEntry tme)
   at System.Windows.Forms.Control.InvokeMarshaledCallbackHelper(Object obj)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Windows.Forms.Control.InvokeMarshaledCallback(ThreadMethodEntry tme)
   at System.Windows.Forms.Control.InvokeMarshaledCallbacks()
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
   at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
   at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
   at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
   at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
   at System.Windows.Forms.Application.Run(Form mainForm)
   at CefSharp.WinForms.Example.Program.Main(String[] args) in D:\Estudos\CefSharp-master\CefSharp.WinForms.Example\Program.cs:line 99

  This exception was originally thrown at this call stack:
    std::_Iterator_base12::_Adopt(std::_Container_base12*) in xmemory
    std::_Vector_const_iterator<std::_Vector_val<std::_Simple_types<scoped_refptr<CefX509Certificate> > > >::_Vector_const_iterator<std::_Vector_val<std::_Simple_types<scoped_refptr<CefX509Certificate> > > >(scoped_refptr<CefX509Certificate>*, std::_Container_base12*) in vector
    std::vector<scoped_refptr<CefX509Certificate>,std::allocator<scoped_refptr<CefX509Certificate> > >::end(void) in vector
    CefSharp::Internals::CefCertificateCallbackWrapper::Select(System::Security::Cryptography::X509Certificates::X509Certificate2^) in CefCertificateCallbackWrapper.h
    CefSharp.WinForms.Example.Handlers.WinFormsRequestHandler.OnSelectClientCertificate.AnonymousMethod__0() in WinFormsRequestHandler.cs
    CefSharp.WinForms.Example.ControlExtensions.InvokeOnUiThreadIfRequired.AnonymousMethod__0() in ControlExtensions.cs

Inner Exception 1:
AccessViolationException: Tentativa de leitura ou gravação em memória protegida. Normalmente, isso é uma indicação de que outra memória está danificada.

[amaitland]

Interesting, thanks!

It looks like we no longer have a valid reference to the vector.

As a test can you try selecting a certificate without switching to the UI Thread. E.g. the following.
I'm not worried about selecting the correct certificate, just that it doesn't cause an exception.

protected override bool OnSelectClientCertificate(IWebBrowser chromiumWebBrowser, IBrowser browser, bool isProxy, string host, int port, X509Certificate2Collection certificates, ISelectClientCertificateCallback callback)
{
	callback.Select(certificates[0]);
	return true;
}

If that works we might be able to copy the contents of the vector rather than just storing a reference to resolve the problem.

---

Just to clarify something, your code passes in a X509Certificate2 instance that isn't necessarily in the X509Certificate2Collection that's passed as a param.

certificates is the list of certificates to choose from; this list has already been pruned by Chromium so that it only contains certificates from issuers that the server trusts.

As per https://magpcss.org/ceforum/apidocs3/projects/(default)/CefRequestHandler.html#OnSelectClientCertificate(CefRefPtr%3CCefBrowser%3E,bool,constCefString&,int,constX509CertificateList&,CefRefPtr%3CCefSelectClientCertificateCallback%3E)

This should be the same as passing in null to ISelectClientCertificateCallback .Select, so I don't actually think this has anything to do with the exception you are seeing.

[valdeircaires]

Calling directly within the "OnSelectClientCertificate" method without the "InvokeOnUiThreadIfRequired" does not present the exception.

protected override bool OnSelectClientCertificate(IWebBrowser chromiumWebBrowser, IBrowser browser, bool isProxy, string host, int port, X509Certificate2Collection certificates, ISelectClientCertificateCallback callback)
{
callback.Select(certificates[0]);
return true;
}

Thank you for your help.

[amaitland]

Interesting thanks. Looks like the vector is being freed. If I make a change are you able to confirm works?

[thracx]

The solution above fixed my problem as well, many thanks to you all! (#2948)

@amaitland Your idea of doing a content copying is likely the best solution.