GetFieldDescriptorAt results in [Access violation - code c0000005] about credprovider.net

[martijnvanschie]

Finally found my issue (or actually bug)

It was the GetCredentialAt method that had the bug. It did indeed always return a null and never set the actual ICredentialProviderCredential when found. So that was my access violation, there was no provider set.

It works now.

Thanks for taking the time to look into this.

[SteveSyfuhs]

Presumably that's because GetBitmapValue is having issues. What does that code look like?

[martijnvanschie]

I first thought of that too as the WinDbg trace shows this being called. But the function is pretty slim and i've tested it with different types of fields.

I think that credprovhost!_GetBitmapData+0x44: tries to access a pointer and fails there before even calling the COM object.

Here is the code.

        public virtual int GetBitmapValue(uint dwFieldID, out IntPtr phbmp)
        {
            Debug.Write("GetBitmapValue");
            Diagnostics.LogMethodEntry();
            phbmp = IntPtr.Zero;

            try
            {
                return HRESULT.S_OK;
            }
            catch (Exception ex)
            {
                _logger.Error(ex, $"{ex.Message}");
                return HRESULT.E_UNEXPECTED;
            }
            finally
            {
                Diagnostics.LogMethodExit();
            }
        }

[SteveSyfuhs]

Do you have a better stack trace on this error? _GetBitmapData isn't doing anything particularly interesting. It first checks if this is an ICredentialProviderCredential3 and if so asks to call GetBitmapBufferValue. Yours most likely isn't a v3 so it skips this. It then calls GetBitmapValue, which makes a copy if the pointer isn't nullptr, and then finally returns any error or OK.

[martijnvanschie]

Hi.

This stacktrace is all i have at the moment. The error accured in native code So there is no .Net runtime error and i can't use visual studio for debugging. I went with debugging using WinDbg. This is what i got. Tips are welcome of course

Also i cant find much on V3 credentials. Can you point me to some resources. I'm using v2 so maybee that is the issue.

This one is really getting on my nerves :)

[martijnvanschie]

This is the stack btw. So perhaps a bit more than i thought. Hope it helps.

[SteveSyfuhs]

Hmm. That all looks right. Nothing is jumping out. Can you share a simplified repo? I'm stepping through my code and its not obvious where this differs to cause the issue?

[martijnvanschie]

Thought this all looked oke to me too. I'm thinking in the direction of build settings that differ but i checked the csproj and they are not that different.

I will need to clean up some code before i can share as this is a work project so cant just put it out there.
Let me get back to you. Thanx for the offer at least :)

[martijnvanschie]

Hi again.

I finally shared a trimmed down version of my repo with you. If you could take a look that would be much appreciated.