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

[Gustavo A. R. Silva]

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 <k...@kernel.org>

Reviewed-by: Gustavo A. R. Silva <gustavo...@kernel.org>

Thanks!
-Gustavo

---
Cc: Johannes Berg <johan...@sipsolutions.net>
Cc: <linux-wirel...@vger.kernel.org>
---
  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;

  }