linux-kernel - Re: 2.6.25.3: su gets stuck for root

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Message-ID: <20080514054634.GA2645@1wt.eu>
Date:	Wed, 14 May 2008 07:46:34 +0200
From:	Willy Tarreau <w@....eu>
To:	Harald Dunkel <harald.dunkel@...nline.de>
Cc:	Vegard Nossum <vegard.nossum@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: 2.6.25.3: su gets stuck for root

On Wed, May 14, 2008 at 06:55:24AM +0200, Harald Dunkel wrote:
> Willy Tarreau wrote:
> >
> >even as root ? Because if you run strace on "su" as a user, you will
> >lose the setuid which may change the conditions.
> >
> 
> It gets stuck _only_ if I am root. Running su without root permission
> is no problem.

OK. That's quite strange.

> As written before, If I kick out the "stty intr '^C'" from root's
> .bashrc, then the second su succeeds. Running the stty command
> manually in this new shell is no problem.
> 
> Can you reproduce this problem? It doesn't need XWindow or any
> special user. Simply login as root on tty2, and run "su". If it
> gets stuck, then you could login on tty3 and kill -9 ### the blocking
> stty.

I tried (I'm on 2.6.25.1). But neither "su", "su willy" nor "stty intr ^C"
caused such a problem unfortunately.

You may want to ask several people to test in the same environment as
yours (same distro, etc...) in order to find whether it's a user-land
bug or a kernel bug. Most likely it's a kernel bug or side effect which
is triggered by your version of su or stty.

> Regards
> 
> Harri

Willy

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