[PATCH AUTOSEL 5.4 003/175] ath9x: Fix stack-out-of-bounds Write in ath9k_hif_usb_rx_cb

[Sasha Levin]

From: Qiujun Huang <hqjagain@xxxxxxxxx>

[ Upstream commit 19d6c375d671ce9949a864fb9a03e19f5487b4d3 ]

Add barrier to accessing the stack array skb_pool.

The case reported by syzbot:
https://lore.kernel.org/linux-usb/0000000000003d7c1505a2168418@xxxxxxxxxx
BUG: KASAN: stack-out-of-bounds in ath9k_hif_usb_rx_stream
drivers/net/wireless/ath/ath9k/hif_usb.c:626 [inline]
BUG: KASAN: stack-out-of-bounds in ath9k_hif_usb_rx_cb+0xdf6/0xf70
drivers/net/wireless/ath/ath9k/hif_usb.c:666
Write of size 8 at addr ffff8881db309a28 by task swapper/1/0

Call Trace:
ath9k_hif_usb_rx_stream drivers/net/wireless/ath/ath9k/hif_usb.c:626
[inline]
ath9k_hif_usb_rx_cb+0xdf6/0xf70
drivers/net/wireless/ath/ath9k/hif_usb.c:666
__usb_hcd_giveback_urb+0x1f2/0x470 drivers/usb/core/hcd.c:1648
usb_hcd_giveback_urb+0x368/0x420 drivers/usb/core/hcd.c:1713
dummy_timer+0x1258/0x32ae drivers/usb/gadget/udc/dummy_hcd.c:1966
call_timer_fn+0x195/0x6f0 kernel/time/timer.c:1404
expire_timers kernel/time/timer.c:1449 [inline]
__run_timers kernel/time/timer.c:1773 [inline]
__run_timers kernel/time/timer.c:1740 [inline]
run_timer_softirq+0x5f9/0x1500 kernel/time/timer.c:1786

Reported-and-tested-by: syzbot+d403396d4df67ad0bd5f@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Qiujun Huang <hqjagain@xxxxxxxxx>
Signed-off-by: Kalle Valo <kvalo@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20200404041838.10426-5-hqjagain@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/net/wireless/ath/ath9k/hif_usb.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c
index dd0c32379375..c4a2b7201ce3 100644
--- a/drivers/net/wireless/ath/ath9k/hif_usb.c
+++ b/drivers/net/wireless/ath/ath9k/hif_usb.c
@@ -612,6 +612,11 @@ static void ath9k_hif_usb_rx_stream(struct hif_device_usb *hif_dev,
 			hif_dev->remain_skb = nskb;
 			spin_unlock(&hif_dev->rx_lock);
 		} else {
+			if (pool_index == MAX_PKT_NUM_IN_TRANSFER) {
+				dev_err(&hif_dev->udev->dev,
+					"ath9k_htc: over RX MAX_PKT_NUM\n");
+				goto err;
+			}
 			nskb = __dev_alloc_skb(pkt_len + 32, GFP_ATOMIC);
 			if (!nskb) {
 				dev_err(&hif_dev->udev->dev,
-- 
2.25.1