Re: [RESEND][PATCH v2] register_console: prevent adding the same console twice

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Fri, Aug 02, 2013 at 12:23:34PM +0200, Andreas Bießmann wrote:
> This patch guards the console_drivers list to be corrupted. The
> for_each_console() macro insist on a strictly forward list ended by NULL:
> 
>  con0->next->con1->next->NULL
> 
> Without this patch it may happen easily to destroy this list for example by
> adding 'earlyprintk' twice, especially on embedded devices where the early
> console is often a single static instance.  This will result in the following
> list:
> 
>  con0->next->con0
> 
> This in turn will result in an endless loop in console_unlock() later on by
> printing the first __log_buf line endlessly.
> 
> Signed-off-by: Andreas Bießmann <andreas@biessmann.de>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Kay Sievers <kay@vrfy.org>
> Cc: Ben Hutchings <ben@decadent.org.uk>
> Cc: stable@vger.kernel.org

It's a nice "feature", but I fail to see how this is worthy of going
into the stable tree, as it's not fixing a kernel error, only a typo by
a user.

thanks,

greg k-h