Bug 1411847 - ssh login hangs with motd >= 11010 chars
Summary: ssh login hangs with motd >= 11010 chars
Keywords:
Status: CLOSED DUPLICATE of bug 1404018
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: openssh
Version: 7.3
Hardware: x86_64
OS: Linux
unspecified
high
Target Milestone: rc
: ---
Assignee: Jakub Jelen
QA Contact: BaseOS QE Security Team
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2017-01-10 15:51 UTC by Phil
Modified: 2017-01-18 14:45 UTC (History)
0 users

Fixed In Version: openssh-6.6.1p1-33.el7
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2017-01-18 14:45:27 UTC
Target Upstream Version:


Attachments (Terms of Use)

Description Phil 2017-01-10 15:51:45 UTC
Description of problem:

when logging in to a server with a big /etc/motd (11010 chars and up) as an unprivileged user, the ssh connection hangs.

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

6.6.1p1-31.el7 affected
6.6.1p1-25.el7_2 NOT affected

How reproducible:

always

Steps to Reproduce:

1. root@server:~ $ python -c 'print "a"*11009' > /etc/motd
2. "ls -l /etc/motd" should show a size of 11010 bytes
3. login to the server

Actual results:

login hangs after the environments get sent, right before the motd should show up

Expected results:

successful login

Additional info:

- login works fine with:
root@test:~ $ python -c 'print "a"*11008' > /etc/motd
root@test:~ $ ls -l /etc/motd 
-rw-r--r--. 1 root root 11009 10. Jan 16:27 /etc/motd

- login hangs with:
root@test:~ $ python -c 'print "a"*11009' > /etc/motd  
root@test:~ $ ls -l /etc/motd 
-rw-r--r--. 1 root root 11010 10. Jan 16:28 /etc/motd

- tested with a fresh CentOS 7.3.1611 installation without any modifications[1]
- the connection hangs even on connections to 127.0.0.1
- the used shell is not relevant (tested with bash and tcsh)
- selinux not relevant (tested with enforcing and permissive)
- username length is not relevant (tested with "phil" and "philippe")
- does NOT affect root


[1]
%packages --nocore
bash
tcsh
openssh-server
pam
selinux-policy-targeted
yum
%end

Comment 1 Jakub Jelen 2017-01-10 16:01:21 UTC
Thank you for a verbose analysis. This has been already reported, fixed and update will be released soon. Stay tuned.
Please, contact your Red Hat support if you need hotfix earlier.

Comment 3 Jakub Jelen 2017-01-18 14:45:27 UTC

*** This bug has been marked as a duplicate of bug 1404018 ***


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