linux-kernel - Re: [PATCH] wifi: mt76: Replace strlcpy with strscpy

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Message-ID: <202307271001.13EA5FB@keescook>
Date:   Thu, 27 Jul 2023 10:02:28 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Azeem Shaikh <azeemshaikh38@...il.com>
Cc:     Felix Fietkau <nbd@....name>,
        Lorenzo Bianconi <lorenzo@...nel.org>,
        Ryder Lee <ryder.lee@...iatek.com>,
        linux-hardening@...r.kernel.org,
        Shayne Chen <shayne.chen@...iatek.com>,
        Sean Wang <sean.wang@...iatek.com>,
        linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kalle Valo <kvalo@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH] wifi: mt76: Replace strlcpy with strscpy

On Tue, Jul 18, 2023 at 12:38:37AM -0400, Azeem Shaikh wrote:
> On Wed, Jul 12, 2023 at 7:54 PM Kees Cook <keescook@...omium.org> wrote:
> >
> > On Mon, Jul 03, 2023 at 06:12:56PM +0000, Azeem Shaikh wrote:
> > > strlcpy() reads the entire source buffer first.
> > > This read may exceed the destination size limit.
> > > This is both inefficient and can lead to linear read
> > > overflows if a source string is not NUL-terminated [1].
> > > In an effort to remove strlcpy() completely [2], replace
> > > strlcpy() here with strscpy().
> > >
> > > Direct replacement is safe here since DEV_ASSIGN is only used by
> > > TRACE macros and the return values are ignored.
> > >
> > > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
> > > [2] https://github.com/KSPP/linux/issues/89
> > >
> > > Signed-off-by: Azeem Shaikh <azeemshaikh38@...il.com>
> >
> > Looks good -- thing is using return values from the macros.
> 
> Just to confirm, you mean *not* using return values from the macros?

I thought I'd replied to this, but I see it didn't happen: yes, I meant
"not using return values". Sorry for the confusion!

-- 
Kees Cook