[Pkg-samba-maint] Bug#495653: Bug#495653: samba: libc free()crash in smbd

[Steve Langasek]

tags 495653 confirmed
retitle 495653 samba: crash with [homes], security=share, and valid users = %S
thanks

On Tue, Aug 26, 2008 at 12:11:23AM +0200, Uwe Schindler wrote:
> > On Mon, Aug 25, 2008 at 06:41:46PM +0200, Christian Perrier wrote:
> > > Then I started samba with this and tried connecting to my home
> > > directory (after "smbpasswd bubulle"):

> > Before running 'smbpasswd', did you also set 'lanman auth = yes' in the
> > smb.conf?

> > If not, your smbpasswd entry only has an NTLM password hash, it doesn't
> > have
> > a LanMan password hash; so connecting to samba in share security mode will
> > not be possible.

> > The server hang is a bug anyway, but it may be that it only happens in a
> > server misconfiguration.

> > Perhaps we should patch param/loadparm.c to not allow security=share
> > without
> > lanman auth = yes?

> Yes, it is a bug. When connecting with Windows XP you cannot choose
> authentication scheme.

> Adding:
> 	lanman auth = yes
> does crash, too! The above configuration always worked with prior samba
> versions. And indeed, setting security to "user", stops the bug, but is not
> the behaviour, I want.

I've tested using the smb.conf you provided, which enabled me to narrow this
down to a reproducible test case.  The case where this breaks is when
security = share is set, you're connecting to a [homes] autoshare, *and*
valid users = %S is set.

Strangely, even though 'valid users' shouldn't be required at all when using
security=share, if I remove the 'valid users' setting from my config I'm
able to connect to other users' home shares.  Otherwise, I would suggest
this as a workaround.

On the other hand, I'm not sure why you say that setting security=user is
not the behavior you want.  What doesn't work the way you want it to?  It's
certainly far more secure than having to enable lanman auth when your
clients are WinXP...

In any case, I will try to isolate the fix for this bug and forward
upstream.

-- 
Steve Langasek                   Give me a lever long enough and a Free OS
Debian Developer                   to set it on, and I can move the world.
Ubuntu Developer                                    http://www.debian.org/
slangasek at ubuntu.com                                     vorlon at debian.org