Re: AUDIT of 2.5.15 copy_to/from_user

Alan Cox
2002-05-19T17:16:15Z

> On Sun, 19 May 2002, Alan Cox wrote:
> > >
> > > On the emu10k1 driver we use access_ok(VERIFY_READ) once at the beginning
> > > of the write() routine to check we can access the user buffer. After that
> > > we always use __copy_from_user() and we trust it not to fail. Is this
> > > correct, or not?
> >
> > This is correct
>
> Am I right to read that as "This is a correct description of what is
> currently done in the emu10k1 driver, but what it is doing is incorrect"?

It seems correct in what it is doing, to a point. copy_from_user won't ever
fail in a fatal manner. It may not copy enough data and zero fill returning
an error code. Reporting of that error isnt required however, its just
good manners