From: Amol Kumar Lad <amolk@ishoni.com>
To: Ravi <kravi26@yahoo.com>
Cc: linux-mm@kvack.org
Subject: Re: copy_from_user
Date: 23 Dec 2002 10:02:18 -0500 [thread overview]
Message-ID: <1040655739.4986.86.camel@amol.in.ishoni.com> (raw)
In-Reply-To: <20021223012106.10392.qmail@web12301.mail.yahoo.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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prev parent reply other threads:[~2002-12-23 15:02 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-12-21 23:26 copy_from_user Amol Kumar Lad
2002-12-23 1:21 ` copy_from_user Ravi
2002-12-23 15:02 ` Amol Kumar Lad [this message]
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