Re: AUDIT of 2.5.15 copy_to/from_user

Hugh Dickins
2002-05-19T16:58:43Z

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"?

> Static once off checks are done in access_ok
> Dynamic checks are doing in __copy_from_*
>
> Which are which depends on the platform. On x86 for example access_ok
> is basically a check for 0->0xBFFFFFFF range and no more

Hugh