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Bug 2234604

Summary: ssh fails when connecting to WinSSHD with gss-kex
Product: Red Hat Enterprise Linux 8 Reporter: Frank Hirtz <fhirtz>
Component: opensshAssignee: Dmitry Belyavskiy <dbelyavs>
Status: CLOSED MIGRATED QA Contact: BaseOS QE Security Team <qe-baseos-security>
Severity: medium Docs Contact:
Priority: medium    
Version: 8.8CC: jjelen
Target Milestone: rcKeywords: MigratedToJIRA, Triaged
Target Release: ---Flags: pm-rhel: mirror+
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2023-09-20 04:27:47 UTC Type: Bug
Regression: --- Mount Type: ---
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Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description Frank Hirtz 2023-08-24 20:30:53 UTC
Description of problem:
When connecting to a server which identifies as "9.26 FlowSsh: Bitvise SSH Server (WinSSHD) 9.26", the connection fails with "ssh_packet_read: internal error: buffer is read-only"

There is a PR with a fix at https://github.com/openssh-gsskex/openssh-gsskex/pull/19 that's been languishing for years at this point.

There's a partial port of this into the RHEL release, but it's not quite complete and thus fails 

When does this behavior occur? Frequency? Repeatedly? At certain times?
Always

Version-Release number of selected component (if applicable):
RHEL 8.8 x64


Additional info:
https://www.bitvise.com/ssh-server-download

Comment 1 Frank Hirtz 2023-08-24 20:35:14 UTC
Having a look at the sources of what we're shipping in RHEL8, it looks like we have that patch already included. This is the current stream 8, but this hasn't changed in some time so far as I can tell from the changelog. Here's the part of the patch which adds the gexgssc.c file which is what the referenced commit targets:

https://gitlab.com/redhat/centos-stream/rpms/openssh/-/blob/c8s/openssh-8.0p1-gssapi-keyex.patch?ref_type=heads#L1511

I had a look and it appears that the requested changes are already mostly here, but the current patch doesn't quite include all of the change. 

Compare:
https://gitlab.com/redhat/centos-stream/rpms/openssh/-/blob/c8s/openssh-8.0p1-gssapi-keyex.patch?ref_type=heads#L1680
https://github.com/Jakuje/openssh-gsskex/blob/063e1a255b53abde1147522f9aceccfd2a7ceb9b/kexgssc.c#L171

Our patch still has if ((r = sshpkt_getb_froms(ssh, &server_host_key_blob)) != 0)
The fixed code has if ((r = sshpkt_get_string(ssh, &tmp, &tmp_len)) != 0)

Comment 2 Dmitry Belyavskiy 2023-08-25 09:55:57 UTC
Yes, the change you refer to was applied in RHEL 9 but not in RHEL 8 series.

We currently don't have plans to make an errata for RHEL 8, unfortunately.

Comment 5 RHEL Program Management 2023-09-20 04:25:47 UTC
Issue migration from Bugzilla to Jira is in process at this time. This will be the last message in Jira copied from the Bugzilla bug.

Comment 6 RHEL Program Management 2023-09-20 04:27:47 UTC
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