wifi: mt76: add memory barrier to SDIO queue kick

[ Upstream commit 5f54237ad798f41cb6a503271aa9ca47188cfb9b ]

Ensure the entry has been fully updated before SDIO bus worker access
it. This patch would fix potential memory risk in both mt7663s and
mt7921s.

Fixes: 764dee47e2c1 ("mt76: sdio: move common code in mt76_sdio module")
Signed-off-by: Deren Wu <deren.wu@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/wireless/mediatek/mt76/sdio.c b/drivers/net/wireless/mediatek/mt76/sdio.c
index 0ec308f..176207f 100644 (file)
--- a/drivers/net/wireless/mediatek/mt76/sdio.c
+++ b/drivers/net/wireless/mediatek/mt76/sdio.c
@@ -562,6 +562,10 @@ mt76s_tx_queue_skb_raw(struct mt76_dev *dev, struct mt76_queue *q,
 
        q->entry[q->head].buf_sz = len;
        q->entry[q->head].skb = skb;
+
+       /* ensure the entry fully updated before bus access */
+       smp_wmb();
+
        q->head = (q->head + 1) % q->ndesc;
        q->queued++;