Bug 3411

Summary:	8.9 regression: "ssh -XAf localhost xeyes" uses 100% CPU
Product:	Portable OpenSSH	Reporter:	harri
Component:	ssh	Assignee:	Assigned to nobody <unassigned-bugs>
Status:	CLOSED DUPLICATE
Severity:	normal	CC:	djm, post+bugzilla.mindrot.org
Priority:	P5
Version:	8.9p1
Hardware:	Other
OS:	Linux

Description harri 2022-03-22 19:51:24 AEDT

Hi folks,

a simple ssh command like

	ssh -XAf localhost xeyes

uses 100% CPU when the terminal goes away. There is no such problem for
openssh 8.8 (or for using nohup).

Same problem for other apps instead of xeyes (e.g. xterm) and for remote hosts instead of localhost.

configure command line:

./configure --prefix=/usr/local/stow/openssh-8.9p1 --with-privsep-path=/tmp/empty

I got the same problem using Debian's ssh client, see https://bugs.debian.org/1007822


Regards

Harri

Comment 1 harri 2022-03-22 19:56:34 AEDT

Better command line to reproduce the problem:

xterm -e 'ssh -XAf localhost xeyes'

Comment 2 Damien Miller 2022-03-23 10:43:14 AEDT

I couldn't reproduce this, but does the patch attached to bug #3405 help? https://bugzilla.mindrot.org/attachment.cgi?id=3581

Comment 3 harri 2022-03-23 17:11:28 AEDT

Seems to be an improvement. The high CPU load is gone. strace shows that ssh isn't polling anymore. Moving back to the old ssh: Problem is back.

Comment 4 Damien Miller 2022-03-31 08:26:54 AEDT


*** This bug has been marked as a duplicate of bug 3405 ***

Comment 5 Damien Miller 2022-04-08 12:12:54 AEST

closing bug resolved during openssh-9.0 release cycle