linux-hardening - Re: [PATCH] net: sched: Replace strlcpy with strscpy

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Message-ID: <CALs4sv27N_egw=x+3xwV7f1OOjUov2LfoxQGFfYm_CBBtyx1iw@mail.gmail.com>
Date:   Mon, 10 Jul 2023 09:56:53 +0530
From:   Pavan Chebbi <pavan.chebbi@...adcom.com>
To:     Azeem Shaikh <azeemshaikh38@...il.com>
Cc:     Jamal Hadi Salim <jhs@...atatu.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Jiri Pirko <jiri@...nulli.us>, linux-hardening@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Subject: Re: [PATCH] net: sched: Replace strlcpy with strscpy

On Mon, Jul 10, 2023 at 8:37 AM Azeem Shaikh <azeemshaikh38@...il.com> 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 return value of -errno
> is used to check for truncation instead of sizeof(dest).
>
> [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 to me.
Reviewed-by: Pavan Chebbi <pavan.chebbi@...adcom.com>

>  net/sched/act_api.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/sched/act_api.c b/net/sched/act_api.c
> index f7887f42d542..9d3f26bf0440 100644
> --- a/net/sched/act_api.c
> +++ b/net/sched/act_api.c
> @@ -1320,7 +1320,7 @@ struct tc_action_ops *tc_action_load_ops(struct nlattr *nla, bool police,
>                         return ERR_PTR(err);
>                 }
>         } else {
> -               if (strlcpy(act_name, "police", IFNAMSIZ) >= IFNAMSIZ) {
> +               if (strscpy(act_name, "police", IFNAMSIZ) < 0) {
>                         NL_SET_ERR_MSG(extack, "TC action name too long");
>                         return ERR_PTR(-EINVAL);
>                 }
> --
> 2.41.0.255.g8b1d071c50-goog
>
>
>

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