Re: Why does x86_64 support a SuSE-specific ioctl?

["H. Peter Anvin" <hpa@zytor.com>]

Followup to:  <p73adltqz9g.fsf@oldwotan.suse.de>
By author:    Andi Kleen <ak@suse.de>
In newsgroup: linux.dev.kernel
>
> Adrian Bunk <bunk@fs.tum.de> writes:
> > 
> > TIOCGDEV is (as the comment above indicates) in neither 2.4.20-pre9 nor in
> > 2.5.40 and I'm wondering why the x86_64 kernel supports a SuSE-specific
> > i386 ioctl?
> 
> Why not? 
> 
> I resubmitted the TIOCGDEV patch to Marcelo now, which implements it 
> for the console device.
> 

> -
> +		case TIOCGDEV:
> +			return put_user (kdev_t_to_nr (real_tty->device), (unsigned int*) arg);

This is broken -- you're returning a dev_t as an unsigned int.  On
i386 that means overwriting two bytes of userspace you shouldn't be,
and if dev_t > unsigned int in the future it has the opposite problem.
Note that this is different from TIOCGPTN which return a pts number,
not a dev_t.

	-hpa
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