[PATCH 1/2] wifi: nl80211: validate nested MBSSID IE blobs

[Zhao Li <enderaoelyther@gmail.com>]

Validate each nested NL80211_ATTR_MBSSID_ELEMS entry as a well-formed
information-element stream before storing it for beacon construction.

RNR parsing already validates each nested blob with validate_ie_attr()
before storing it. Apply the same syntactic IE validation to MBSSID
entries before counting and copying their data and length pointers.

Fixes: dc1e3cb8da8b ("nl80211: MBSSID and EMA support in AP mode")
Assisted-by: Codex:gpt-5.5
Assisted-by: Claude:claude-opus-4.8
Signed-off-by: Zhao Li <enderaoelyther@gmail.com>
---
 net/wireless/nl80211.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 76c537a6e8b52..2baf1bef0bbd2 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -6321,7 +6321,8 @@ static int nl80211_parse_mbssid_config(struct wiphy *wiphy,
 }
 
 static struct cfg80211_mbssid_elems *
-nl80211_parse_mbssid_elems(struct wiphy *wiphy, struct nlattr *attrs)
+nl80211_parse_mbssid_elems(struct wiphy *wiphy, struct nlattr *attrs,
+			   struct netlink_ext_ack *extack)
 {
 	struct nlattr *nl_elems;
 	struct cfg80211_mbssid_elems *elems;
@@ -6332,6 +6333,12 @@ nl80211_parse_mbssid_elems(struct wiphy *wiphy, struct nlattr *attrs)
 		return ERR_PTR(-EINVAL);
 
 	nla_for_each_nested(nl_elems, attrs, rem_elems) {
+		int ret;
+
+		ret = validate_ie_attr(nl_elems, extack);
+		if (ret)
+			return ERR_PTR(ret);
+
 		if (num_elems >= 255)
 			return ERR_PTR(-EINVAL);
 		num_elems++;
@@ -6503,7 +6510,8 @@ static int nl80211_parse_beacon(struct cfg80211_registered_device *rdev,
 	if (attrs[NL80211_ATTR_MBSSID_ELEMS]) {
 		struct cfg80211_mbssid_elems *mbssid =
 			nl80211_parse_mbssid_elems(&rdev->wiphy,
-						   attrs[NL80211_ATTR_MBSSID_ELEMS]);
+						   attrs[NL80211_ATTR_MBSSID_ELEMS],
+						   extack);
 
 		if (IS_ERR(mbssid))
 			return PTR_ERR(mbssid);
-- 
2.50.1 (Apple Git-155)