Re: [Bugme-new] [Bug 13675] New: sierra_close sometimes crashes upon device removal

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On Tue, 7 Jul 2009, Oliver Neukum wrote:

> Am Dienstag, 7. Juli 2009 16:39:03 schrieb Alan Stern:
> > It does seem unnecessary to keep the minor number tied up merely
> > because the device file is open.  Maybe there's some deeper reason for
> > this I'm not aware of.  In any case, below is an experimental patch you
> > can try out.  It should cause usb-serial to release the minor number as
> > soon as the device is unplugged.  (I haven't tried it myself, so you'll
> > be the first!)
> 
> This endangers system security. Somebody might have permissions to
> use the old device, defined by a major:minor pair, who must not be let use
> the new device.

I don't understand.  Permissions aren't associated with major:minor 
paris; they are associated with device nodes in the filesystem.

So yes, it's possible that an old device node allowing global access
might not be replaced sufficiently quickly by a new node having more
restrictive permissions.  Then a user could open the old node and
thereby gain access to the new device.  But that's unrelated to this 
patch.

Alan Stern

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