[GUACAMOLE-1890] Segfault in RDP Connection Pending Join Handler

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Duplicate
• Affects Version/s: 1.5.4
• Component/s: RDP
• Assignee: Unassigned
• Reporter: Nick Couchman
• Created: 08/Dec/23 02:56
• Updated: 08/Dec/23 11:18
• Resolved: 08/Dec/23 11:18

Description

Well, this makes me really happy - all the development and banging on various revisions of 1.5.4, and I run into this bug shortly after approving/merging the website release.

I've managed to hit just the right combination of...something...to run into a segfault during RDP connections using the 1.5.4 code. The segfault appears to be related to the new join handler/synchronization code:

#0  0x00007ffff6fead00 in pthread_mutex_lock () from /lib64/libpthread.so.0
#1  0x0000000000404fa9 in guac_common_list_lock (list=<optimized out>) at list.c:95
#2  0x00007ffff0d5b8a8 in guac_rdp_pipe_svc_send_pipes (client=<optimized out>, socket=0x7fffec0135a0) at channels/pipe-svc.c:51
#3  0x00007ffff0d62440 in guac_rdp_join_pending_handler (client=0x7fffec0145a0) at client.c:126
#4  0x00007ffff7bc12bd in guac_client_promote_pending_users (data=...) at client.c:197
#5  0x00007ffff39edf5f in timer_sigev_thread () from /lib64/librt.so.1
#6  0x00007ffff6fe8ea5 in start_thread () from /lib64/libpthread.so.0
#7  0x00007ffff58e4b0d in clone () from /lib64/libc.so.6

At the moment, it seems to impact RDP connections where I've also enabled SFTP. If I disable the SFTP component, I am able to complete the RDP connection. So, seems like maybe there's some sort of race condition that the SSH/SFTP connection is introducing that causes it to attempt to lock the list prior to it being initialized.

Issue Links

• duplicates: GUACAMOLE-1140 Starting/joining an RDP connection may segfault depending on timing of underlying RDP/SFTP connection(s)