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