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Windows VDA 1912 CU6 with CWA for Linux 23.02 causes VDA BSOD with USB Redirection enabled


Steven Brown1709154220

Question

We've stumbled on to an interesting issue which caused us a headache for about 10 days.

 

Environment:

Citrix Hypervisor 8.2 CU1 Path 1021 + PVS Accelerator

Windows Server 2016 fully patched

PVS 2203

CVAD 1912 CU6

 

Clients:

HP Thinpro 7.2 (linux-based) fully patched with CWA 2212 (recently upgraded from 2209)

Lenovo Thinkpad T520 with Ubuntu 22.04 fully patched + CWA 2303

 

After upgrading our Thin clients to 2212 we started seeing intermittent VDA crashes ( 1 or 2 per day).   The VDAs are not configured to take a memory dump on crash as the storage requirements would be immense.  There were no "BUGCHECK" or another other such logs on the VDAs to indicate what happened.

 

We initially thought this might be a Xenserver issue and opened a case with Citrix as I found some "VIRIDIAN CRASH" messages in hypervisor.log.  This turned out to be simply a notice that the VM OS had crashed.

 

After doing some research, the same half dozen users started to emerge as a potential cause.

 

We herded the offending users to a separate Delivery Group to lessen the disruptions to the rest of the business.  The reboots followed them for the most part.

 

Upon inspection of the thin client we discovered a pattern of users plugging in an Apple iPhone or Google Pixel (to charge them) which matched perfectly to the crash times on the VDAs.  This pattern repeated itself perfectly over the course of a couple days.

 

We then noticed that USB Client Redirection had been enabled on the VDA via policy and the HP Thinpro is configured (contrary to how the CWA comes from Citrix) to redirect ALL devices to the VDA if redirection is enabled.   I brought out my Thinkpad with Ubuntu and compared the usb.conf files.  Thinpro has a "CONNECT ALL" type statement at the bottom of the file that the stock CWA does not have.

 

By setting up the Thinkpad CWA to redirect USB Class 06 (Imaging) I was able to reproduce the crashing issue with Ubuntu.

 

Interestingly, this doesn't happen the first time you connect the device.  In fact Windows shows a "Device Setup" window if you are logged in as an admin.  The setup.dev.log shows it installs a MTP driver successfully but the window stays up and slowly progressing for about 5 mins.    The iphone never appears in Device Manager.   If you unplug the phone and plug it back in, the VDA crashes with a PNP_DETECTED_FATAL_ERROR.

 

I can run the same test with a Windows CWA and I cannot reproduce the crash and the iphone appears in Device Manager as a "Portable device".

 

I suspect Citrix is using USB over IP to facilitate the Generic USB Redirection so I setup a simple test with my laptop and a VDA.  I installed the USB over IP client on the VDA, the server components on the Laptop and connected them.    The iphone showed up as a "Portable device" and I was able to disconnect and reconnect it at will without any crashes.

 

 

Has anybody else seen a problem like this?    Our solution for now is to disable USB Client Redirection as we don't have a use case for it at the moment.  I think we can all agree that users and clients should not be able to crash a VDA by plugging in a device.   I have a ticket open with Citrix about this.   I was able to produce a full memory dump this afternoon and will be sending that in shortly.

 

 

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Hello Steven,

 

Maybe you should try with VDA 1912 CU7, there is a solved issue about BSOD with reconnections:

 

https://docs.citrix.com/en-us/citrix-virtual-apps-desktops/1912-ltsr/whats-new/cumulative-update-7/fixed-issues.html

 

Quote

VDAs might experience a fatal exception on tdica.sys and display a blue screen. The issue occurs when you are attempting to reconnect to a session. [CVADHELP-21318]

 

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