From: Kees Cook <kees@kernel.org>
Date: Mon, 21 Jul 2025 18:25:22 +0000 (-0700)
Subject: wifi: mac80211: Write cnt before copying in ieee80211_copy_rnr_beacon()
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a37192c432adaec9e8ef29e4ddb319ea2f443aa6;p=thirdparty%2Flinux.git

wifi: mac80211: Write cnt before copying in ieee80211_copy_rnr_beacon()

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@kernel.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://patch.msgid.link/20250721182521.work.540-kees@kernel.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 4f20d57ab913a..2ed07fa121ab7 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;
 }