linux-hardening - Re: [PATCH] net/mediatek: strlcpy withreturn

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Date:   Tue, 13 Jun 2023 12:23:59 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Azeem Shaikh <azeemshaikh38@...il.com>
Cc:     Jakub Kicinski <kuba@...nel.org>, linux-hardening@...r.kernel.org,
        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] net/mediatek: strlcpy withreturn

On Tue, Jun 13, 2023 at 12:34:57AM +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>

Yup double-checked the users of the macros. Looks good to me.

Reviewed-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook