KB277834 breaks smart card logon on Windows XP

[AWS]

I have been trying to determine why our virtual smart card driver no longer allows logon under Windows XP SP3.  After spending some time debugging the driver I found a point at which there was potential for a reader state to not be set correctly.

 Testing this change showed that indeed solved the problem.

 

After cleaning up testing code in the driver, retesting a newly built version showed the same problem again.  Watching the states via WinDbg showed that the reader states are indeed being set to the correct values.  The card tracking notification is being

sent when the card is determined to be present, and the reader state is ending in SCARD_SPECIFIC.  However at this point the OS (scardsvr) no longer sends any further requests to the driver.

 

Retesting the new version under Vista and 7 showed it to be working.  On a hunch I checked to see if the test system received any updates, and it did.  Reviewing the updates produced a list of culprits: KB2778344, KB2799494, KB2758857.  After removing

KB2778344 and retesting showed that the new driver functions as expected.

 

Are there potential changes in the KB that affect the use of smart cards during logon (from the CAD screen)?  Was there a change to the wdm smclib that I don't have on by dev system?

 

Thanks,

Nik

 

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