Re: [Security] Should open TTY device files pin minor numbers?

[david]

On Wed, 29 Jul 2009, H. Peter Anvin wrote:

> On 07/24/2009 10:14 PM, Greg KH wrote:
> > On Thu, Jul 23, 2009 at 02:38:01PM -0400, Alan Stern wrote:
> > > Recent work in the TTY core and in usb-serial has caused a change
> > > in behavior between 2.6.30 and 2.6.31-rc.  Namely, if a USB serial
> > > device is unplugged while a process holds the device file open, the
> > > minor number won't get reused until the process closes the file.
> >
> > That's how the usb-serial code always worked, this is nothing new at
> > all.
> >
> > > For example, if you run minicom over /dev/ttyUSB0, unplug the USB
> > > device while minicom is running, and then plug it in again before
> > > exiting minicom, it will reappear as /dev/ttyUSB1 instead of
> > > /dev/ttyUSB0 (which will be gone).
> >
> > Exactly.  People are used to this by now, it shouldn't be a supprise :)
>
> It is, however, a *very* nasty surprise when the USB bus glitches.

however since the serial adapters will be re-detected in a random order 
it's less nasty than cross-connecting devices and applications silently.

David Lang
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