[PATCH v2] wifi: rtw88: usb: drop RX frames received before the device is started

[YuanZhe Liu]

rtw_usb_probe() submits the bulk-in RX URBs at the end of probe, right
after rtw_register_hw(). A device can already have data queued on that
endpoint, so rtw_usb_read_port_complete() runs and queues the frame on
rtwusb->rx_queue before any interface has been brought up. Submitting
the URBs late does not close that window: the frame can arrive as soon
as they are submitted, which is still before the device is started.

rtw_usb_rx_handler() hands every non-C2H frame to mac80211 without
checking whether the device is running, so ieee80211_rx_irqsafe() runs
while local->started is still false. mac80211 treats that as a driver
bug and warns in ieee80211_rx_list():

  WARNING: net/mac80211/rx.c:5601 at ieee80211_rx_list
   Call Trace:
    <IRQ>
    ieee80211_rx_napi
    ieee80211_rx
    ieee80211_handle_queued_frames
    <TASK>
    rtw_usb_rx_resubmit
    rtw_usb_setup_rx
    rtw_usb_probe

The frame is dropped by mac80211 anyway, and because the URB is
resubmitted from its completion handler, every further frame repeats the
warning, which floods the log until an interface is actually started.

rtw_ops_tx() already drops frames outside of start/stop by checking
RTW_FLAG_RUNNING, which mirrors local->started: it is set at the end of
rtw_core_start() and cleared at the beginning of rtw_core_stop(). Use
the same check in the RX path and free the frame while the device is not
running. This also covers the opposite ordering, where a frame that is
still queued in rtwusb->rx_queue is handed over after the device has
been stopped again.

C2H packets are left untouched: they go to the firmware event queue
handled by rtw_fw_c2h_cmd_rx_irqsafe() and are never passed to mac80211.

Fixes: a82dfd33d123 ("wifi: rtw88: Add common USB chip support")
Cc: stable@xxxxxxxxxxxxxxx
Co-developed-by: Bin Yu <byu@xxxxxxxxxxxxx>
Signed-off-by: Bin Yu <byu@xxxxxxxxxxxxx>
Co-developed-by: Cheng Wen <wencheng@xxxxxxxxxxxxx>
Signed-off-by: Cheng Wen <wencheng@xxxxxxxxxxxxx>
Signed-off-by: YuanZhe Liu <25031212351@xxxxxxxxxxxxxxxxx>
---
Changes in v2:
  - Restructure the check as suggested in review: bail out at the top of
    the data-frame branch with goto skip_packet, and drop the comment.
---
 drivers/net/wireless/realtek/rtw88/usb.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/wireless/realtek/rtw88/usb.c b/drivers/net/wireless/realtek/rtw88/usb.c
index 64e1c3420e0a..dbfe02f7d6f0 100644
--- a/drivers/net/wireless/realtek/rtw88/usb.c
+++ b/drivers/net/wireless/realtek/rtw88/usb.c
@@ -665,6 +665,11 @@ static void rtw_usb_rx_handler(struct work_struct *work)
 			if (pkt_stat.is_c2h) {
 				rtw_fw_c2h_cmd_rx_irqsafe(rtwdev, pkt_offset, skb);
 			} else {
+				if (!test_bit(RTW_FLAG_RUNNING, rtwdev->flags)) {
+					dev_kfree_skb_any(skb);
+					goto skip_packet;
+				}
+
 				skb_pull(skb, pkt_offset);
 				rtw_update_rx_freq_for_invalid(rtwdev, skb,
 							       &rx_status,
-- 
2.34.1