linux-kernel - Re: [PATCH] bail out in mathemu if __copy_to

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Date:	Thu, 2 Nov 2006 00:23:09 +0100
From:	"Jesper Juhl" <jesper.juhl@...il.com>
To:	"Randy Dunlap" <randy.dunlap@...cle.com>
Cc:	linux-kernel@...r.kernel.org, "Linus Torvalds" <torvalds@...l.org>,
	billm@...urbia.net
Subject: Re: [PATCH] bail out in mathemu if __copy_to_user fails

On 02/11/06, Randy Dunlap <randy.dunlap@...cle.com> wrote:
> On Thu, 2 Nov 2006 00:03:16 +0100 Jesper Juhl wrote:
>
> > I believe we should check the return value of
> > __copy_to_user in math-emu/fpu_entry.c and bail out of save_i387_soft() if
> > it fails.
> > This patch does that.
> >
> > This also kills the warning :
> >   arch/i386/math-emu/fpu_entry.c:745: warning: ignoring return value of `__copy_to_user', declared with attribute warn_unused_result
>
>
> http://www.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.19-rc4/2.6.19-rc4-mm1/broken-out/x86_64-mm-i386-mathemu-must-check.patch
>

Ohh. I was not aware of that patch. Let's apply yours, it's so much
more thorough than mine :-)

Thank you for pointing it out.

>
> > Signed-off-by: Jesper Juhl <jesper.juhl@...il.com>
> > ---
> >
> > diff --git a/arch/i386/math-emu/fpu_entry.c b/arch/i386/math-emu/fpu_entry.c
> > index d93f16e..ddf8fa3 100644
> > --- a/arch/i386/math-emu/fpu_entry.c
> > +++ b/arch/i386/math-emu/fpu_entry.c
> > @@ -742,7 +742,8 @@ #ifdef PECULIAR_486
> >    S387->fcs &= ~0xf8000000;
> >    S387->fos |= 0xffff0000;
> >  #endif /* PECULIAR_486 */
> > -  __copy_to_user(d, &S387->cwd, 7*4);
> > +  if (__copy_to_user(d, &S387->cwd, 7*4))
> > +    return -1;
> >    RE_ENTRANT_CHECK_ON;
> >
> >    d += 7*4;
>
>
> ---
> ~Randy
>


-- 
Jesper Juhl <jesper.juhl@...il.com>
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