[GUACAMOLE-424] VNC client segfaults if provided password is incorrect

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.9.13-incubating
• Fix Version/s: 1.0.0
• Component/s: guacamole-server

Environment

VM has installed TightVNC server.

Guacmole server (guacd) installed using steps from here (https://guacamole.incubator.apache.org/doc/gug/installing-guacamole.html)

Guacmole client behind tomcat7

Gucamole client has a postgresql database extension for dynamic user authentication.

Remote protocol - VNC

• Assignee: Unassigned
• Reporter: Ivaylo Petkov Tsankov
• Created: 24/Oct/17 13:41
• Updated: 06/Jan/19 20:42
• Resolved: 15/Nov/17 15:07

Description

Everything works ok with connections which match the remote vnc password of the TightVNC server.

The issue happens when there is a connection in guacmole-client which does not match the remote VNC password of the TightVNC. When I attempt to connect over this connection, the guacd failed with segfault.

Here are guacd logs from the issue:

Oct 13 16:15:01 ip-172-31-18-56 guacd[13924]: VNC server supports protocol version 3.8 (viewer 3.8)
Oct 13 16:15:01 ip-172-31-18-56 guacd[13924]: We have 1 security types to read
Oct 13 16:15:01 ip-172-31-18-56 guacd[13924]: 0) Received security type 2
Oct 13 16:15:01 ip-172-31-18-56 guacd[13924]: Selecting security type 2 (0/1 in the list)
Oct 13 16:15:01 ip-172-31-18-56 guacd[13924]: Selected Security Scheme 2
Oct 13 16:15:01 ip-172-31-18-56 guacd[13924]: VNC connection failed: password check failed!
Oct 13 16:15:01 ip-172-31-18-56 guacd[13924]: Unable to connect to VNC server.
Oct 13 16:15:02 ip-172-31-18-56 guacd[13730]: User is not responding.
Oct 13 16:15:02 ip-172-31-18-56 kernel: [81568.417106] guacd[13733]: segfault at 10 ip 00007f54edf56e62 sp 00007f54a37fdd50 error 4 in libguac-client-vnc.so.0.0.0[7f54edf4e000+13000]
Oct 13 16:15:02 ip-172-31-18-56 guacd[5325]: Connection "$ee148c21-83b7-4e70-9051-c29b51a06c56" removed.
Oct 13 16:15:03 ip-172-31-18-56 guacd[13744]: User is not responding.
Oct 13 16:15:03 ip-172-31-18-56 kernel: [81569.081782] guacd[13747]: segfault at 10 ip 00007f54edf56e62 sp 00007f54df7fdd50 error 4 in libguac-client-vnc.so.0.0.0[7f54edf4e000+13000]
Oct 13 16:15:03 ip-172-31-18-56 guacd[5325]: Connection "$423ac38c-9dfe-4100-b2c6-bf83669aa76a" removed.
Oct 13 16:15:04 ip-172-31-18-56 guacd[13762]: User is not responding.
Oct 13 16:15:04 ip-172-31-18-56 kernel: [81569.985579] guacd[13765]: segfault at 10 ip 00007f54dc5ece62 sp 00007f54ed960d50 error 4 in libguac-client-v

Issue Links

• is duplicated by: GUACAMOLE-388 Segfault upon disconnect in guac_vnc_user_leave_handler()
• is duplicated by: GUACAMOLE-601 VNC segfault when VNC server restarted
• is duplicated by: GUACAMOLE-428 segfault in guac_vnc_user_leave_handler caused by concurrent problem