Re: [RFC PATCH] net: sched: em_text: Replace strncpy() with strscpy_pad()

From: Florian Westphal
Date: Thu Mar 27 2025 - 12:23:56 EST


I Hsin Cheng <richard120310@xxxxxxxxx> wrote:
> The content within "conf.algo" should be a valid NULL-terminated string,
> however "strncpy()" doesn't guarantee that. Use strscpy_pad() to replace
> it to make sure "conf.algo" is NULL-terminated. ( trailing NULL-padding
> if source buffer is shorter. )
>
> Link: https://github.com/KSPP/linux/issues/90
> Signed-off-by: I Hsin Cheng <richard120310@xxxxxxxxx>
> ---
> net/sched/em_text.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/sched/em_text.c b/net/sched/em_text.c
> index 420c66203b17..c78b82931dc4 100644
> --- a/net/sched/em_text.c
> +++ b/net/sched/em_text.c
> @@ -108,7 +108,7 @@ static int em_text_dump(struct sk_buff *skb, struct tcf_ematch *m)
> struct text_match *tm = EM_TEXT_PRIV(m);
> struct tcf_em_text conf;
>
> - strncpy(conf.algo, tm->config->ops->name, sizeof(conf.algo) - 1);
> + strscpy_pad(conf.algo, tm->config->ops->name, sizeof(conf.algo) - 1);

Please drop the 3rd argument and then resend with a fixes tag:
Fixes: d675c989ed2d ("[PKT_SCHED]: Packet classification based on textsearch (ematch)")

As is, the last byte remains uninitialised.