linux-kernel - [PATCH] wifi: mt76: mt7996: avoid null deref in mt7996_stop

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Message-Id: <20250322111354.23800-1-qasdev00@gmail.com>
Date: Sat, 22 Mar 2025 11:13:54 +0000
From: Qasim Ijaz <qasdev00@...il.com>
To: nbd@....name,
	lorenzo@...nel.org,
	ryder.lee@...iatek.com,
	shayne.chen@...iatek.com,
	sean.wang@...iatek.com,
	matthias.bgg@...il.com,
	angelogioacchino.delregno@...labora.com,
	chui-hao.chiu@...iatek.com,
	Bo.Jiao@...iatek.com
Cc: linux-wireless@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-mediatek@...ts.infradead.org
Subject: [PATCH] wifi: mt76: mt7996: avoid null deref in mt7996_stop_phy()

In mt7996_stop_phy() the mt7996_phy structure is 
dereferenced before the null sanity check which could 
lead to a null deref.

Fix by moving the dereference operation after the 
sanity check.

Fixes: 69d54ce7491d ("wifi: mt76: mt7996: switch to single multi-radio wiphy")
Signed-off-by: Qasim Ijaz <qasdev00@...il.com>
---
 drivers/net/wireless/mediatek/mt76/mt7996/main.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7996/main.c b/drivers/net/wireless/mediatek/mt76/mt7996/main.c
index 66575698aef1..88e013577c0d 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7996/main.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7996/main.c
@@ -68,11 +68,13 @@ static int mt7996_start(struct ieee80211_hw *hw)
 
 static void mt7996_stop_phy(struct mt7996_phy *phy)
 {
-	struct mt7996_dev *dev = phy->dev;
+	struct mt7996_dev *dev;
 
 	if (!phy || !test_bit(MT76_STATE_RUNNING, &phy->mt76->state))
 		return;
 
+	dev = phy->dev;
+
 	cancel_delayed_work_sync(&phy->mt76->mac_work);
 
 	mutex_lock(&dev->mt76.mutex);
-- 
2.39.5