[PATCH 1/3] wifi: cfg80211: validate rx/tx MLME callback frame lengths before access

[Zhao Li <enderaoelyther@gmail.com>]

cfg80211_rx_mlme_mgmt() and cfg80211_tx_mlme_mgmt() read the frame
control field without first checking len >= 2, then dispatch into
subtype handlers that assume their fixed fields are present.

Add a frame-control length gate, then validate each subtype's minimum
frame size in an if/else-if chain that mirrors the dispatch logic.
Trace only after the frame is known to be well-formed.

Side effects of this change:
 - The WARN_ON(len < 2) is replaced by a silent early return, since
   these cfg80211 callbacks can legitimately receive short frames from
   drivers.
 - cfg80211_tx_mlme_mgmt() previously routed every non-deauth subtype
   through disassociation handling; it now silently ignores unrecognised
   subtypes.

Assisted-by: Codex:gpt-5.5
Assisted-by: Claude:claude-opus-4.8
Signed-off-by: Zhao Li <enderaoelyther@gmail.com>
---
 net/wireless/mlme.c | 45 +++++++++++++++++++++++++++++++++++++--------
 1 file changed, 37 insertions(+), 8 deletions(-)

diff --git a/net/wireless/mlme.c b/net/wireless/mlme.c
index bd72317c4964e..a0f7b08bfcc9c 100644
--- a/net/wireless/mlme.c
+++ b/net/wireless/mlme.c
@@ -150,19 +150,35 @@ void cfg80211_rx_mlme_mgmt(struct net_device *dev, const u8 *buf, size_t len)
 {
 	struct wireless_dev *wdev = dev->ieee80211_ptr;
 	struct ieee80211_mgmt *mgmt = (void *)buf;
+	__le16 fc;
 
 	lockdep_assert_wiphy(wdev->wiphy);
 
-	trace_cfg80211_rx_mlme_mgmt(dev, buf, len);
+	if (len < sizeof(fc))
+		return;
+
+	fc = mgmt->frame_control;
 
-	if (WARN_ON(len < 2))
+	if (ieee80211_is_auth(fc)) {
+		if (len < offsetofend(struct ieee80211_mgmt, u.auth.status_code))
+			return;
+	} else if (ieee80211_is_deauth(fc)) {
+		if (len < offsetofend(struct ieee80211_mgmt, u.deauth.reason_code))
+			return;
+	} else if (ieee80211_is_disassoc(fc)) {
+		if (len < offsetofend(struct ieee80211_mgmt, u.disassoc.reason_code))
+			return;
+	} else {
 		return;
+	}
+
+	trace_cfg80211_rx_mlme_mgmt(dev, buf, len);
 
-	if (ieee80211_is_auth(mgmt->frame_control))
+	if (ieee80211_is_auth(fc))
 		cfg80211_process_auth(wdev, buf, len);
-	else if (ieee80211_is_deauth(mgmt->frame_control))
+	else if (ieee80211_is_deauth(fc))
 		cfg80211_process_deauth(wdev, buf, len, false);
-	else if (ieee80211_is_disassoc(mgmt->frame_control))
+	else
 		cfg80211_process_disassoc(wdev, buf, len, false);
 }
 EXPORT_SYMBOL(cfg80211_rx_mlme_mgmt);
@@ -215,15 +231,28 @@ void cfg80211_tx_mlme_mgmt(struct net_device *dev, const u8 *buf, size_t len,
 {
 	struct wireless_dev *wdev = dev->ieee80211_ptr;
 	struct ieee80211_mgmt *mgmt = (void *)buf;
+	__le16 fc;
 
 	lockdep_assert_wiphy(wdev->wiphy);
 
-	trace_cfg80211_tx_mlme_mgmt(dev, buf, len, reconnect);
+	if (len < sizeof(fc))
+		return;
 
-	if (WARN_ON(len < 2))
+	fc = mgmt->frame_control;
+
+	if (ieee80211_is_deauth(fc)) {
+		if (len < offsetofend(struct ieee80211_mgmt, u.deauth.reason_code))
+			return;
+	} else if (ieee80211_is_disassoc(fc)) {
+		if (len < offsetofend(struct ieee80211_mgmt, u.disassoc.reason_code))
+			return;
+	} else {
 		return;
+	}
+
+	trace_cfg80211_tx_mlme_mgmt(dev, buf, len, reconnect);
 
-	if (ieee80211_is_deauth(mgmt->frame_control))
+	if (ieee80211_is_deauth(fc))
 		cfg80211_process_deauth(wdev, buf, len, reconnect);
 	else
 		cfg80211_process_disassoc(wdev, buf, len, reconnect);
-- 
2.50.1 (Apple Git-155)