Re: [PATCH] protect against buggy drivers

[Greg KH <greg@kroah.com>]

On Fri, Oct 08, 2004 at 01:29:40PM -0400, Richard B. Johnson wrote:
> On Fri, 8 Oct 2004, Greg KH wrote:
> 
> >On Fri, Oct 08, 2004 at 09:53:41AM -0700, Stephen Hemminger wrote:
> >>+	    strlen(name) >= KOBJ_NAME_LEN ||
> >
> >There's no need for this check, if we fix the other usage of
> >cdev->kobj.name in this file to use the proper kobject_name() and
> >kobject_set_name() functions.
> 
> Well the module name is passed in register/unregister_chrdev(). It
> was not documented as the allowed length of the name so it was
> possible to install a device and then only "partially" uninstall
> the device so a subsequent open of the device-file would crash
> the kernel.  A device name of :
> 
> 	"Octrangle Contrabulator"  23 characters
> 
> ... in a test program was sufficiently-long to kill the kernel.
> I recommend truncating any name to an acceptable length. This
> would show up in /proc/iomem, etc., prompting the developer
> to shorten the name.
> 
> Also, the new length of 20 characters is probably too short.
> There was no such limitation on 2.4.x, where many modules
> are being ported from.

That's why I said this check should not go in, and the cdev code fixed
to use the proper functions.  That would enable you to have as long as a
name as you wanted to.

thanks,

greg k-h