bugzilla-daemon at bugzilla.mindrot.org
2007-Oct-26 00:14 UTC
[Bug 1384] New: OpenSSH clients causing deadlocks
https://bugzilla.mindrot.org/show_bug.cgi?id=1384 Summary: OpenSSH clients causing deadlocks Classification: Unclassified Product: Portable OpenSSH Version: 4.7p1 Platform: All OS/Version: All Status: NEW Severity: normal Priority: P2 Component: ssh AssignedTo: bitbucket at mindrot.org ReportedBy: jca at newtonesque.kicks-ass.net OpenSSH clients (in all releases I have been able to test with, including 4.7p1) when talking protocol version 2 seem to be sending SSH_MSG_CHANNEL_REQUEST messages with the want_reply field set to 0. This leads to a problem when the server they interact with does not support the service being requested. If the channel request is for, say, command execution, and the server does not support such a capability, a standards-compliant server won't send anything back at that point - because the OpenSSH client has set the want_reply field to 0. However, the OpenSSH client seems to be assuming that this request will always be successful. That is, that servers will always support this capability. Because of this assumption, a deadlock ensues. This is a bug in the OpenSSH client. It is true that for some channel requests (e.g. things like, say, X11 and XON/XOFF requests) the client can proceed (and does proceed) without the server replying anything, but for others (most notably SHELL and EXEC) it can't. The OpenSSH client should always set want_reply to 1 when sending such requests, in order to prevent deadlocks like the one described above. -- Configure bugmail: https://bugzilla.mindrot.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are watching the assignee of the bug.
bugzilla-daemon at bugzilla.mindrot.org
2007-Nov-03 00:14 UTC
[Bug 1384] client hangs against server lacking common channel requests
https://bugzilla.mindrot.org/show_bug.cgi?id=1384 Damien Miller <djm at mindrot.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Summary|OpenSSH clients causing |client hangs against server |deadlocks |lacking common channel | |requests Severity|normal |minor CC| |djm at mindrot.org -- Configure bugmail: https://bugzilla.mindrot.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are watching the assignee of the bug. You are watching someone on the CC list of the bug.
bugzilla-daemon at bugzilla.mindrot.org
2008-May-08 13:12 UTC
[Bug 1384] client hangs against server lacking common channel requests
https://bugzilla.mindrot.org/show_bug.cgi?id=1384 --- Comment #1 from Damien Miller <djm at mindrot.org> 2008-05-08 23:12:18 --- A fix for this bug has been committed and will be in OpenSSH 5.1:> CVSROOT: /cvs > Module name: src > Changes by: djm at cvs.openbsd.org 2008/05/08 07:06:11 > > Modified files: > usr.bin/ssh : clientloop.c clientloop.h ssh.c > > Log message: > Use new channel status confirmation callback system to properly deal > with "important" channel requests that fail, in particular command exec, > shell and subsystem requests. Previously we would optimistically assume > that the requests would always succeed, which could cause hangs if they > did not (e.g. when the server runs out of fds) or were unimplemented by > the server (bz #1384) > > Also, properly report failing multiplex channel requests via the mux > client stderr (subject to LogLevel in the mux master) - better than > silently failing. > > most bits ok markus@ (as part of a larger diff)-- Configure bugmail: https://bugzilla.mindrot.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are watching the assignee of the bug. You are watching someone on the CC list of the bug.
bugzilla-daemon at bugzilla.mindrot.org
2008-May-08 13:13 UTC
[Bug 1384] client hangs against server lacking common channel requests
https://bugzilla.mindrot.org/show_bug.cgi?id=1384 Damien Miller <djm at mindrot.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED Resolution| |FIXED -- Configure bugmail: https://bugzilla.mindrot.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are watching the assignee of the bug. You are watching someone on the CC list of the bug.
bugzilla-daemon at bugzilla.mindrot.org
2008-Jul-14 02:30 UTC
[Bug 1384] client hangs against server lacking common channel requests
https://bugzilla.mindrot.org/show_bug.cgi?id=1384 Damien Miller <djm at mindrot.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Blocks| |1452 -- Configure bugmail: https://bugzilla.mindrot.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are watching the assignee of the bug. You are watching someone on the CC list of the bug.
bugzilla-daemon at bugzilla.mindrot.org
2008-Jul-22 02:20 UTC
[Bug 1384] client hangs against server lacking common channel requests
https://bugzilla.mindrot.org/show_bug.cgi?id=1384 Damien Miller <djm at mindrot.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|RESOLVED |CLOSED --- Comment #2 from Damien Miller <djm at mindrot.org> 2008-07-22 12:20:12 --- Mass update RESOLVED->CLOSED after release of openssh-5.1 -- Configure bugmail: https://bugzilla.mindrot.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are watching the assignee of the bug. You are watching someone on the CC list of the bug.