i386/123330: Enabling samba wins in nsswitch.conf causes sshd, ftpd, etc services to die

[Shelby Cain]

>Number:         123330
>Category:       i386
>Synopsis:       Enabling samba wins in nsswitch.conf causes sshd, ftpd, etc services to die
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-i386
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri May 02 14:30:02 UTC 2008
>Closed-Date:
>Last-Modified:
>Originator:     Shelby Cain
>Release:        7.0-REL
>Organization:
>Environment:
FreeBSD freebsdlol.localdomain 7.0-RELEASE FreeBSD 7.0-RELEASE #1: Mon Apr 14 17:59:26 CDT 2008     root at freebsdlol.localdomain:/usr/obj/usr/src/sys/MYKERN  i386
>Description:
Background:  I have a mixed home network of Windows, Linux and (now) FreeBSD.  In order to facilitate easy communication between the systems I install Samaba and enable wins resolution in nsswitch.conf on all non-windows boxes so that netbios name resolution can occur.

Problem:  Once I've added "hosts: files dns wins" to my nsswitch.conf on FreeBSD any system service that appears to rely on name resolution will segfault when it attempts to handle incoming connections.

I realize that netbios name resolution functionality probably isn't a super high priority but causing a denial of service by enabling something that should work without issue strikes me as a serious bug so I marked it as such.  I also tried getting a backtrace from one of the ftpd.core files and gdb listed thousands of stack frames which I assume means some form of stack corruption has occurred.

>How-To-Repeat:
1) Install FreeBSD 7.0-i386.
2) Enable various network services such as sshd and ftpd.
3) Establish ssh session to the server.
4) Build and install Samba3 from ports.
5) Change hosts line in /etc/nsswitch.conf to read "hosts: files dns wins"
6) Verify that you can resolve windows netbios names via a tool like ping.  Do not close your existing ssh session at this point as you'll be unable to log back in!
7) Attempt to create a new ssh or ftp session.  The attempt will fail and a message about the (I assume forked) process being terminated with signal 11 will be logged in /var/log/messages.  This will continue for as long as "wins" is left in /etc/nsswitch.conf.
8) Removing the "wins" entry will restore normal behavior.
>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted: