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Message-ID: <07a220351baa1e6851b90c961aade0ce6d26bcf6.camel@redhat.com>
Subject: Re: [PATCH] drivers/comedi: copy userspace array safely
From:   Philipp Stanner <pstanner@redhat.com>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Ian Abbott <abbotti@mev.co.uk>,
        H Hartley Sweeten <hsweeten@visionengravers.com>,
        Ivan Orlov <ivan.orlov0322@gmail.com>,
        Benjamin Tissoires <benjamin.tissoires@redhat.com>,
        linux-kernel@vger.kernel.org, Dave Airlie <airlied@redhat.com>
Date:   Fri, 03 Nov 2023 10:11:06 +0100
In-Reply-To: <2023110348-drained-tameness-b943@gregkh>
References: <20231102190848.51376-2-pstanner@redhat.com>
         <2023110348-drained-tameness-b943@gregkh>
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On Fri, 2023-11-03 at 06:53 +0100, Greg Kroah-Hartman wrote:
> On Thu, Nov 02, 2023 at 08:08:49PM +0100, Philipp Stanner wrote:
> > comedi_fops.c utilizes memdup_user() to copy a userspace array. This
> > does not check for an overflow.
>=20
> Is there potential for an overflow today?

None that I'm aware of, no. This is more about establishing the new
function as the standard for array-copying, thereby improving
readability and maybe robustness in case of future changes.

>=20
> >=20
> > Use the new wrapper memdup_array_user() to copy the array more safely.
>=20
> How about saying something like:
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0"Use the new function mem=
dup_array_user() in case things change
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0in the future which would=
 prevent overflows if something were to
> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0change in the size of the=
 structures".
>=20
> Or something to the affect of "all is good today, but make it easy to be
> correct in the future as well".

Yes, good idea. I'll send a better wording

P.

>=20
> thanks,
>=20
> greg k-h
>=20