On Thu, Sep 18, 2025 at 12:12 PM Dilip Modi <[email protected]>
wrote:

> Hello Guacamole Community,
>
> We are experiencing a crash in guacd in our production environment and
> would appreciate any insights you might have. The crash appears to be
> related to the RDP protocol, specifically when loading a Dynamic Virtual
> Channel (DVC).
>
> *Summary of the Issue:*
>
> The guacd process crashes during an RDP connection. The last log message
> from the crashing process indicates it was attempting to load the disp DVC.
> The backtrace confirms the crash occurs within the FreeRDP
> library's drdynvc handling thread.
>

Does it always crash? Or only under certain conditions? Is it random? Or
easily reproducible?


> *Logs:*
>
> Here is the relevant log snippet from guacd just before it crashed. The
> process ID is 1432425.
>
> plaintext
>
>
>
> Sep 16 12:47:23 guacd[1432425]: 2025-09-16 12:47:23.368484 guacd[1432425]:
> DEBUG:#011Loading Dynamic Virtual Channel disp
>
> Sep 16 12:47:26 guacd[1565]: 2025-09-16 12:47:26.274395 guacd[1565]:
> DEBUG:#011shutdown is sent successfully [1432425]
>
> *Backtrace:*
>
> The backtrace of the crashing thread (LWP 1432468) points directly
> to drdynvc_virtual_channel_client_thread.
>
> plaintext
>
>
>
> #0  0x00007ff54031da31 in StreamPool_Take () from
> /opt/zscaler/lib64/libwinpr2.so.2
>
> #1  0x00007ff54041be5c in drdynvc_virtual_channel_client_thread () from
> /opt/zscaler/lib64/libfreerdp-client2.so.2
>
> #2  0x00007ff54034aa75 in thread_launcher () from
> /opt/zscaler/lib64/libwinpr2.so.2
>
> #3  0x00007ff544e8a19a in start_thread () from /usr/lib64/libc.so.6
>
> #4  0x00007ff544f0f240 in clone3 () from /usr/lib64/libc.so.6
>
>
Based on this backtrace, I'd say that the crash is happening entirely in
the FreeRDP library and not in the guacd code, at all. I could well be
mistaken about that, but all of the files referenced appear to be
FreeRDP-related.

-Nick

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