[PATCH v1 1/1] wifi: mt76: mt792x: Fix memory leak in SDIO TX path

[Eason Lai <eason.lai@mediatek.com>]

From: Eason Lai <Eason.Lai@mediatek.com>

When tx_prepare_skb() returns an error in the SDIO TX path, the
skb is not freed, leading to a memory leak. This can occur when
zero-length frames (such as WNM NULL frames) are dropped to prevent
potential hardware TX hangs.

Fix this by properly releasing the skb with ieee80211_tx_status_ext()
when tx_prepare_skb() fails.

Fixes: b747fa343817 ("mt76: mt7915: drop zero-length packet to avoid Tx hang")
Signed-off-by: Eason Lai <Eason.Lai@mediatek.com>
---
 drivers/net/wireless/mediatek/mt76/sdio.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/mediatek/mt76/sdio.c b/drivers/net/wireless/mediatek/mt76/sdio.c
index 8bae77c761be..ba5f123f7e39 100644
--- a/drivers/net/wireless/mediatek/mt76/sdio.c
+++ b/drivers/net/wireless/mediatek/mt76/sdio.c
@@ -519,6 +519,10 @@ mt76s_tx_queue_skb(struct mt76_phy *phy, struct mt76_queue *q,
 		   enum mt76_txq_id qid, struct sk_buff *skb,
 		   struct mt76_wcid *wcid, struct ieee80211_sta *sta)
 {
+	struct ieee80211_tx_status status = {
+		.sta = sta,
+	};
+
 	struct mt76_tx_info tx_info = {
 		.skb = skb,
 	};
@@ -531,8 +535,13 @@ mt76s_tx_queue_skb(struct mt76_phy *phy, struct mt76_queue *q,
 
 	skb->prev = skb->next = NULL;
 	err = dev->drv->tx_prepare_skb(dev, NULL, qid, wcid, sta, &tx_info);
-	if (err < 0)
+	if (err < 0) {
+		status.skb = tx_info.skb;
+		spin_lock_bh(&dev->rx_lock);
+		ieee80211_tx_status_ext(dev->hw, &status);
+		spin_unlock_bh(&dev->rx_lock);
 		return err;
+	}
 
 	q->entry[q->head].skb = tx_info.skb;
 	q->entry[q->head].buf_sz = len;
-- 
2.45.2