Re: copy_from_user

[Amol Kumar Lad <amolk@ishoni.com>]

yeah..u are right... how stupid of me... I should have read whole
function... I thought..aceess_ok should make such check...

thanks
Amol


On Sun, 2002-12-22 at 20:21, Ravi wrote:
> 
> --- Amol Kumar Lad <amolk@ishoni.com> wrote:
> 
> >   Suppose kernel tries to do copy_from_user from a pointer
> > that does not have any mapping. i.e. not in any VMA (and not
> in
> >  stack area too..). 
> > Now (for 1386)
> > access_ok --> __range_ok
> > Suppose the 'from' ptr is within range then how kernel is
> > making sure that 'from' is invalid ??
> > The page fault handler will see that 'from' has no mapping and
> > it will die.. 
>  
> I believe this is handled using the 'fixup' code in
> __copy_user_zeroing().
> I don't understand the code well though, but I do know that it
> works :)
> 
> -Ravi.
> 
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