Re: [PATCH] wifi: mac80211: Write cnt before copying in ieee80211_copy_rnr_beacon()

["Gustavo A. R. Silva" <gustavo@xxxxxxxxxxxxxx>]

On 21/07/25 12:25, Kees Cook wrote:
> While I caught the need for setting cnt early in nl80211_parse_rnr_elems()
> in the original annotation of struct cfg80211_rnr_elems with __counted_by,
> I missed a similar pattern in ieee80211_copy_rnr_beacon(). Fix this by
> moving the cnt assignment to before the loop.
>
> Fixes: 7b6d7087031b ("wifi: cfg80211: Annotate struct cfg80211_rnr_elems with __counted_by")
> Signed-off-by: Kees Cook <kees@xxxxxxxxxx>

Reviewed-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>

Thanks!
-Gustavo

> ---
> Cc: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
> Cc: <linux-wireless@xxxxxxxxxxxxxxx>
> ---
>   net/mac80211/cfg.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
> index 4f20d57ab913..2ed07fa121ab 100644
> --- a/net/mac80211/cfg.c
> +++ b/net/mac80211/cfg.c
> @@ -1176,13 +1176,13 @@ ieee80211_copy_rnr_beacon(u8 *pos, struct cfg80211_rnr_elems *dst,
>   {
>   	int i, offset = 0;
>   
> +	dst->cnt = src->cnt;
>   	for (i = 0; i < src->cnt; i++) {
>   		memcpy(pos + offset, src->elem[i].data, src->elem[i].len);
>   		dst->elem[i].len = src->elem[i].len;
>   		dst->elem[i].data = pos + offset;
>   		offset += dst->elem[i].len;
>   	}
> -	dst->cnt = src->cnt;
>   
>   	return offset;
>   }