[PATCH rtw-next v5 0/4] wifi: fixes for rtw89

[PATCH rtw-next v5 0/4] wifi: fixes for rtw89

[Fedor Pchelkin]

v5: - respin at 'rtw-next' (series applies to 'rtw' as well, just in case)
    - further changelog below --- in the patches

v4: https://lore.kernel.org/linux-wireless/20250917095302.2908617-1-pchelkin@ispras.ru/
    - drop USB patch to handle that in a separate series
    - further changelog below --- in the patches

v3: https://lore.kernel.org/linux-wireless/20250828211245.178843-1-pchelkin@ispras.ru/
    - further improvements for fix for use-after-free in
      rtw89_core_tx_kick_off_and_wait(), see changelog below --- in the patch
    - add patch 3/5 for USB case

v2: https://lore.kernel.org/linux-wireless/20250827120603.723548-1-pchelkin@ispras.ru/
    - rework fix for use-after-free in rtw89_core_tx_kick_off_and_wait() (Zong-Zhe)
    - add patches 2/4 and 3/4 for another issues discovered while reworking
    - use rtw tree instead of rtw-next

v1: https://lore.kernel.org/linux-wireless/20250820141441.106156-1-pchelkin@ispras.ru/

Fedor Pchelkin (4):
  wifi: rtw89: fix use-after-free in rtw89_core_tx_kick_off_and_wait()
  wifi: rtw89: avoid possible TX wait initialization race
  wifi: rtw89: fix leak in rtw89_core_send_nullfunc()
  wifi: rtw89: avoid circular locking dependency in ser_state_run()

 drivers/net/wireless/realtek/rtw89/core.c | 66 +++++++++++++++--------
 drivers/net/wireless/realtek/rtw89/core.h | 38 +++++++++++--
 drivers/net/wireless/realtek/rtw89/pci.c  |  5 +-
 drivers/net/wireless/realtek/rtw89/ser.c  |  5 +-
 4 files changed, 85 insertions(+), 29 deletions(-)

-- 
2.51.0

[PATCH rtw-next v5 1/4] wifi: rtw89: fix use-after-free in rtw89_core_tx_kick_off_and_wait()

[Fedor Pchelkin]

There is a bug observed when rtw89_core_tx_kick_off_and_wait() tries to
access already freed skb_data:

 BUG: KFENCE: use-after-free write in rtw89_core_tx_kick_off_and_wait drivers/net/wireless/realtek/rtw89/core.c:1110

 CPU: 6 UID: 0 PID: 41377 Comm: kworker/u64:24 Not tainted  6.17.0-rc1+ #1 PREEMPT(lazy)
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS edk2-20250523-14.fc42 05/23/2025
 Workqueue: events_unbound cfg80211_wiphy_work [cfg80211]

 Use-after-free write at 0x0000000020309d9d (in kfence-#251):
 rtw89_core_tx_kick_off_and_wait drivers/net/wireless/realtek/rtw89/core.c:1110
 rtw89_core_scan_complete drivers/net/wireless/realtek/rtw89/core.c:5338
 rtw89_hw_scan_complete_cb drivers/net/wireless/realtek/rtw89/fw.c:7979
 rtw89_chanctx_proceed_cb drivers/net/wireless/realtek/rtw89/chan.c:3165
 rtw89_chanctx_proceed drivers/net/wireless/realtek/rtw89/chan.h:141
 rtw89_hw_scan_complete drivers/net/wireless/realtek/rtw89/fw.c:8012
 rtw89_mac_c2h_scanofld_rsp drivers/net/wireless/realtek/rtw89/mac.c:5059
 rtw89_fw_c2h_work drivers/net/wireless/realtek/rtw89/fw.c:6758
 process_one_work kernel/workqueue.c:3241
 worker_thread kernel/workqueue.c:3400
 kthread kernel/kthread.c:463
 ret_from_fork arch/x86/kernel/process.c:154
 ret_from_fork_asm arch/x86/entry/entry_64.S:258

 kfence-#251: 0x0000000056e2393d-0x000000009943cb62, size=232, cache=skbuff_head_cache

 allocated by task 41377 on cpu 6 at 77869.159548s (0.009551s ago):
 __alloc_skb net/core/skbuff.c:659
 __netdev_alloc_skb net/core/skbuff.c:734
 ieee80211_nullfunc_get net/mac80211/tx.c:5844
 rtw89_core_send_nullfunc drivers/net/wireless/realtek/rtw89/core.c:3431
 rtw89_core_scan_complete drivers/net/wireless/realtek/rtw89/core.c:5338
 rtw89_hw_scan_complete_cb drivers/net/wireless/realtek/rtw89/fw.c:7979
 rtw89_chanctx_proceed_cb drivers/net/wireless/realtek/rtw89/chan.c:3165
 rtw89_chanctx_proceed drivers/net/wireless/realtek/rtw89/chan.c:3194
 rtw89_hw_scan_complete drivers/net/wireless/realtek/rtw89/fw.c:8012
 rtw89_mac_c2h_scanofld_rsp drivers/net/wireless/realtek/rtw89/mac.c:5059
 rtw89_fw_c2h_work drivers/net/wireless/realtek/rtw89/fw.c:6758
 process_one_work kernel/workqueue.c:3241
 worker_thread kernel/workqueue.c:3400
 kthread kernel/kthread.c:463
 ret_from_fork arch/x86/kernel/process.c:154
 ret_from_fork_asm arch/x86/entry/entry_64.S:258

 freed by task 1045 on cpu 9 at 77869.168393s (0.001557s ago):
 ieee80211_tx_status_skb net/mac80211/status.c:1117
 rtw89_pci_release_txwd_skb drivers/net/wireless/realtek/rtw89/pci.c:564
 rtw89_pci_release_tx_skbs.isra.0 drivers/net/wireless/realtek/rtw89/pci.c:651
 rtw89_pci_release_tx drivers/net/wireless/realtek/rtw89/pci.c:676
 rtw89_pci_napi_poll drivers/net/wireless/realtek/rtw89/pci.c:4238
 __napi_poll net/core/dev.c:7495
 net_rx_action net/core/dev.c:7557 net/core/dev.c:7684
 handle_softirqs kernel/softirq.c:580
 do_softirq.part.0 kernel/softirq.c:480
 __local_bh_enable_ip kernel/softirq.c:407
 rtw89_pci_interrupt_threadfn drivers/net/wireless/realtek/rtw89/pci.c:927
 irq_thread_fn kernel/irq/manage.c:1133
 irq_thread kernel/irq/manage.c:1257
 kthread kernel/kthread.c:463
 ret_from_fork arch/x86/kernel/process.c:154
 ret_from_fork_asm arch/x86/entry/entry_64.S:258

It is a consequence of a race between the waiting and the signaling side
of the completion:

            Waiting thread                            Completing thread

rtw89_core_tx_kick_off_and_wait()
  rcu_assign_pointer(skb_data->wait, wait)
  /* start waiting */
  wait_for_completion_timeout()
                                                rtw89_pci_tx_status()
                                                  rtw89_core_tx_wait_complete()
                                                    rcu_read_lock()
                                                    /* signals completion and
                                                     * proceeds further
                                                     */
                                                    complete(&wait->completion)
                                                    rcu_read_unlock()
                                                  ...
                                                  /* frees skb_data */
                                                  ieee80211_tx_status_ni()
  /* returns (exit status doesn't matter) */
  wait_for_completion_timeout()
  ...
  /* accesses the already freed skb_data */
  rcu_assign_pointer(skb_data->wait, NULL)

The completing side might proceed and free the underlying skb even before
the waiting side is fully awoken and run to execution.  Actually the race
happens regardless of wait_for_completion_timeout() exit status, e.g.
the waiting side may hit a timeout and the concurrent completing side is
still able to free the skb.

Skbs which are sent by rtw89_core_tx_kick_off_and_wait() are owned by the
driver.  They don't come from core ieee80211 stack so no need to pass them
to ieee80211_tx_status_ni() on completing side.

Introduce a work function which will act as a garbage collector for
rtw89_tx_wait_info objects and the associated skbs.  Thus no potentially
heavy locks are required on the completing side.

Found by Linux Verification Center (linuxtesting.org).

Fixes: 1ae5ca615285 ("wifi: rtw89: add function to wait for completion of TX skbs")
Cc: stable@vger.kernel.org
Suggested-by: Zong-Zhe Yang <kevin_yang@realtek.com>
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
---

v5: - use completion_done() and delayed work (Ping-Ke)

v4: - fill wait's fields before publishing (Zong-Zhe)
    - leave dev_kfree_skb_any + kfree_rcu for tx_wait release (Zong-Zhe)

v3: - decrease waiting timeout in rtw89_tx_wait_work() (Zong-Zhe)
    - clear tx_waits list from rtw89_hci_reset(), too (Zong-Zhe)
    - keep RCU updating for skb_data->wait (Zong-Zhe)
    - keep the old order of calls in rtw89_pci_tx_status() (Zong-Zhe)
    - drop wait->finished as complete_all() would make the completion be
      done permanently

v2: - use a work function to manage release of tx_waits and associated skbs (Zong-Zhe)

 drivers/net/wireless/realtek/rtw89/core.c | 30 +++++++++++++++----
 drivers/net/wireless/realtek/rtw89/core.h | 35 +++++++++++++++++++++--
 drivers/net/wireless/realtek/rtw89/pci.c  |  3 +-
 drivers/net/wireless/realtek/rtw89/ser.c  |  2 ++
 4 files changed, 61 insertions(+), 9 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtw89/core.c b/drivers/net/wireless/realtek/rtw89/core.c
index fe059c4a6b55..ec467ae0e9e6 100644
--- a/drivers/net/wireless/realtek/rtw89/core.c
+++ b/drivers/net/wireless/realtek/rtw89/core.c
@@ -1135,6 +1135,14 @@ rtw89_core_tx_update_desc_info(struct rtw89_dev *rtwdev,
 	}
 }
 
+static void rtw89_tx_wait_work(struct wiphy *wiphy, struct wiphy_work *work)
+{
+	struct rtw89_dev *rtwdev = container_of(work, struct rtw89_dev,
+						tx_wait_work.work);
+
+	rtw89_tx_wait_list_clear(rtwdev);
+}
+
 void rtw89_core_tx_kick_off(struct rtw89_dev *rtwdev, u8 qsel)
 {
 	u8 ch_dma;
@@ -1152,6 +1160,8 @@ int rtw89_core_tx_kick_off_and_wait(struct rtw89_dev *rtwdev, struct sk_buff *sk
 	unsigned long time_left;
 	int ret = 0;
 
+	lockdep_assert_wiphy(rtwdev->hw->wiphy);
+
 	wait = kzalloc(sizeof(*wait), GFP_KERNEL);
 	if (!wait) {
 		rtw89_core_tx_kick_off(rtwdev, qsel);
@@ -1159,18 +1169,23 @@ int rtw89_core_tx_kick_off_and_wait(struct rtw89_dev *rtwdev, struct sk_buff *sk
 	}
 
 	init_completion(&wait->completion);
+	wait->skb = skb;
 	rcu_assign_pointer(skb_data->wait, wait);
 
 	rtw89_core_tx_kick_off(rtwdev, qsel);
 	time_left = wait_for_completion_timeout(&wait->completion,
 						msecs_to_jiffies(timeout));
-	if (time_left == 0)
-		ret = -ETIMEDOUT;
-	else if (!wait->tx_done)
-		ret = -EAGAIN;
 
-	rcu_assign_pointer(skb_data->wait, NULL);
-	kfree_rcu(wait, rcu_head);
+	if (time_left == 0) {
+		ret = -ETIMEDOUT;
+		list_add_tail(&wait->list, &rtwdev->tx_waits);
+		wiphy_delayed_work_queue(rtwdev->hw->wiphy, &rtwdev->tx_wait_work,
+					 RTW89_TX_WAIT_WORK_TIMEOUT);
+	} else {
+		if (!wait->tx_done)
+			ret = -EAGAIN;
+		rtw89_tx_wait_release(wait);
+	}
 
 	return ret;
 }
@@ -5548,6 +5563,7 @@ void rtw89_core_stop(struct rtw89_dev *rtwdev)
 	wiphy_work_cancel(wiphy, &btc->dhcp_notify_work);
 	wiphy_work_cancel(wiphy, &btc->icmp_notify_work);
 	cancel_delayed_work_sync(&rtwdev->txq_reinvoke_work);
+	wiphy_delayed_work_cancel(wiphy, &rtwdev->tx_wait_work);
 	wiphy_delayed_work_cancel(wiphy, &rtwdev->track_work);
 	wiphy_delayed_work_cancel(wiphy, &rtwdev->track_ps_work);
 	wiphy_delayed_work_cancel(wiphy, &rtwdev->chanctx_work);
@@ -5773,6 +5789,7 @@ int rtw89_core_init(struct rtw89_dev *rtwdev)
 		INIT_LIST_HEAD(&rtwdev->scan_info.pkt_list[band]);
 	}
 	INIT_LIST_HEAD(&rtwdev->scan_info.chan_list);
+	INIT_LIST_HEAD(&rtwdev->tx_waits);
 	INIT_WORK(&rtwdev->ba_work, rtw89_core_ba_work);
 	INIT_WORK(&rtwdev->txq_work, rtw89_core_txq_work);
 	INIT_DELAYED_WORK(&rtwdev->txq_reinvoke_work, rtw89_core_txq_reinvoke_work);
@@ -5784,6 +5801,7 @@ int rtw89_core_init(struct rtw89_dev *rtwdev)
 	wiphy_delayed_work_init(&rtwdev->coex_rfk_chk_work, rtw89_coex_rfk_chk_work);
 	wiphy_delayed_work_init(&rtwdev->cfo_track_work, rtw89_phy_cfo_track_work);
 	wiphy_delayed_work_init(&rtwdev->mcc_prepare_done_work, rtw89_mcc_prepare_done_work);
+	wiphy_delayed_work_init(&rtwdev->tx_wait_work, rtw89_tx_wait_work);
 	INIT_DELAYED_WORK(&rtwdev->forbid_ba_work, rtw89_forbid_ba_work);
 	wiphy_delayed_work_init(&rtwdev->antdiv_work, rtw89_phy_antdiv_work);
 	rtwdev->txq_wq = alloc_workqueue("rtw89_tx_wq", WQ_UNBOUND | WQ_HIGHPRI, 0);
diff --git a/drivers/net/wireless/realtek/rtw89/core.h b/drivers/net/wireless/realtek/rtw89/core.h
index 3d4ad2ffb75c..d15fa70eb4dc 100644
--- a/drivers/net/wireless/realtek/rtw89/core.h
+++ b/drivers/net/wireless/realtek/rtw89/core.h
@@ -3507,9 +3507,12 @@ struct rtw89_phy_rate_pattern {
 	bool enable;
 };
 
+#define RTW89_TX_WAIT_WORK_TIMEOUT msecs_to_jiffies(500)
 struct rtw89_tx_wait_info {
 	struct rcu_head rcu_head;
+	struct list_head list;
 	struct completion completion;
+	struct sk_buff *skb;
 	bool tx_done;
 };
 
@@ -6000,6 +6003,9 @@ struct rtw89_dev {
 	/* used to protect rpwm */
 	spinlock_t rpwm_lock;
 
+	struct list_head tx_waits;
+	struct wiphy_delayed_work tx_wait_work;
+
 	struct rtw89_cam_info cam_info;
 
 	struct sk_buff_head c2h_queue;
@@ -6256,6 +6262,26 @@ rtw89_assoc_link_rcu_dereference(struct rtw89_dev *rtwdev, u8 macid)
 	list_first_entry_or_null(&p->dlink_pool, typeof(*p->links_inst), dlink_schd); \
 })
 
+static inline void rtw89_tx_wait_release(struct rtw89_tx_wait_info *wait)
+{
+	dev_kfree_skb_any(wait->skb);
+	kfree_rcu(wait, rcu_head);
+}
+
+static inline void rtw89_tx_wait_list_clear(struct rtw89_dev *rtwdev)
+{
+	struct rtw89_tx_wait_info *wait, *tmp;
+
+	lockdep_assert_wiphy(rtwdev->hw->wiphy);
+
+	list_for_each_entry_safe(wait, tmp, &rtwdev->tx_waits, list) {
+		if (!completion_done(&wait->completion))
+			continue;
+		list_del(&wait->list);
+		rtw89_tx_wait_release(wait);
+	}
+}
+
 static inline int rtw89_hci_tx_write(struct rtw89_dev *rtwdev,
 				     struct rtw89_core_tx_request *tx_req)
 {
@@ -6265,6 +6291,7 @@ static inline int rtw89_hci_tx_write(struct rtw89_dev *rtwdev,
 static inline void rtw89_hci_reset(struct rtw89_dev *rtwdev)
 {
 	rtwdev->hci.ops->reset(rtwdev);
+	rtw89_tx_wait_list_clear(rtwdev);
 }
 
 static inline int rtw89_hci_start(struct rtw89_dev *rtwdev)
@@ -7345,11 +7372,12 @@ static inline struct sk_buff *rtw89_alloc_skb_for_rx(struct rtw89_dev *rtwdev,
 	return dev_alloc_skb(length);
 }
 
-static inline void rtw89_core_tx_wait_complete(struct rtw89_dev *rtwdev,
+static inline bool rtw89_core_tx_wait_complete(struct rtw89_dev *rtwdev,
 					       struct rtw89_tx_skb_data *skb_data,
 					       bool tx_done)
 {
 	struct rtw89_tx_wait_info *wait;
+	bool ret = false;
 
 	rcu_read_lock();
 
@@ -7357,11 +7385,14 @@ static inline void rtw89_core_tx_wait_complete(struct rtw89_dev *rtwdev,
 	if (!wait)
 		goto out;
 
+	ret = true;
 	wait->tx_done = tx_done;
-	complete(&wait->completion);
+	/* Don't access skb anymore after completion */
+	complete_all(&wait->completion);
 
 out:
 	rcu_read_unlock();
+	return ret;
 }
 
 static inline bool rtw89_is_mlo_1_1(struct rtw89_dev *rtwdev)
diff --git a/drivers/net/wireless/realtek/rtw89/pci.c b/drivers/net/wireless/realtek/rtw89/pci.c
index c8286eb84276..8dd91d867ea6 100644
--- a/drivers/net/wireless/realtek/rtw89/pci.c
+++ b/drivers/net/wireless/realtek/rtw89/pci.c
@@ -464,7 +464,8 @@ static void rtw89_pci_tx_status(struct rtw89_dev *rtwdev,
 	struct rtw89_tx_skb_data *skb_data = RTW89_TX_SKB_CB(skb);
 	struct ieee80211_tx_info *info;
 
-	rtw89_core_tx_wait_complete(rtwdev, skb_data, tx_status == RTW89_TX_DONE);
+	if (rtw89_core_tx_wait_complete(rtwdev, skb_data, tx_status == RTW89_TX_DONE))
+		return;
 
 	info = IEEE80211_SKB_CB(skb);
 	ieee80211_tx_info_clear_status(info);
diff --git a/drivers/net/wireless/realtek/rtw89/ser.c b/drivers/net/wireless/realtek/rtw89/ser.c
index bb39fdbcba0d..fe7beff8c424 100644
--- a/drivers/net/wireless/realtek/rtw89/ser.c
+++ b/drivers/net/wireless/realtek/rtw89/ser.c
@@ -502,7 +502,9 @@ static void ser_reset_trx_st_hdl(struct rtw89_ser *ser, u8 evt)
 		}
 
 		drv_stop_rx(ser);
+		wiphy_lock(wiphy);
 		drv_trx_reset(ser);
+		wiphy_unlock(wiphy);
 
 		/* wait m3 */
 		hal_send_m2_event(ser);
-- 
2.51.0

[PATCH rtw-next v5 2/4] wifi: rtw89: avoid possible TX wait initialization race

[Fedor Pchelkin]

The value of skb_data->wait indicates whether skb is passed on to the
core mac80211 stack or released by the driver itself.  Make sure that by
the time skb is added to txwd queue and becomes visible to the completing
side, it has already allocated and initialized TX wait related data (in
case it's needed).

This is found by code review and addresses a possible race scenario
described below:

      Waiting thread                          Completing thread

rtw89_core_send_nullfunc()
  rtw89_core_tx_write_link()
    ...
    rtw89_pci_txwd_submit()
      skb_data->wait = NULL
      /* add skb to the queue */
      skb_queue_tail(&txwd->queue, skb)

  /* another thread (e.g. rtw89_ops_tx) performs TX kick off for the same queue */

                                            rtw89_pci_napi_poll()
                                            ...
                                              rtw89_pci_release_txwd_skb()
                                                /* get skb from the queue */
                                                skb_unlink(skb, &txwd->queue)
                                                rtw89_pci_tx_status()
                                                  rtw89_core_tx_wait_complete()
                                                  /* use incorrect skb_data->wait */
  rtw89_core_tx_kick_off_and_wait()
  /* assign skb_data->wait but too late */

Found by Linux Verification Center (linuxtesting.org).

Fixes: 1ae5ca615285 ("wifi: rtw89: add function to wait for completion of TX skbs")
Cc: stable@vger.kernel.org
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
---

v5: - update the changelog to reflect that the potential race scenario
      was found by code review
    - pass wait as an argument to rtw89_core_tx_kick_off_and_wait()

v4: - use wiphy_dereference (Zong-Zhe)
    - move wait->skb assignment place 

 drivers/net/wireless/realtek/rtw89/core.c | 39 +++++++++++++----------
 drivers/net/wireless/realtek/rtw89/core.h |  3 +-
 drivers/net/wireless/realtek/rtw89/pci.c  |  2 --
 3 files changed, 24 insertions(+), 20 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtw89/core.c b/drivers/net/wireless/realtek/rtw89/core.c
index ec467ae0e9e6..1f44c7fc1c5e 100644
--- a/drivers/net/wireless/realtek/rtw89/core.c
+++ b/drivers/net/wireless/realtek/rtw89/core.c
@@ -1153,25 +1153,14 @@ void rtw89_core_tx_kick_off(struct rtw89_dev *rtwdev, u8 qsel)
 }
 
 int rtw89_core_tx_kick_off_and_wait(struct rtw89_dev *rtwdev, struct sk_buff *skb,
-				    int qsel, unsigned int timeout)
+				    struct rtw89_tx_wait_info *wait, int qsel,
+				    unsigned int timeout)
 {
-	struct rtw89_tx_skb_data *skb_data = RTW89_TX_SKB_CB(skb);
-	struct rtw89_tx_wait_info *wait;
 	unsigned long time_left;
 	int ret = 0;
 
 	lockdep_assert_wiphy(rtwdev->hw->wiphy);
 
-	wait = kzalloc(sizeof(*wait), GFP_KERNEL);
-	if (!wait) {
-		rtw89_core_tx_kick_off(rtwdev, qsel);
-		return 0;
-	}
-
-	init_completion(&wait->completion);
-	wait->skb = skb;
-	rcu_assign_pointer(skb_data->wait, wait);
-
 	rtw89_core_tx_kick_off(rtwdev, qsel);
 	time_left = wait_for_completion_timeout(&wait->completion,
 						msecs_to_jiffies(timeout));
@@ -1234,10 +1223,12 @@ int rtw89_h2c_tx(struct rtw89_dev *rtwdev,
 static int rtw89_core_tx_write_link(struct rtw89_dev *rtwdev,
 				    struct rtw89_vif_link *rtwvif_link,
 				    struct rtw89_sta_link *rtwsta_link,
-				    struct sk_buff *skb, int *qsel, bool sw_mld)
+				    struct sk_buff *skb, int *qsel, bool sw_mld,
+				    struct rtw89_tx_wait_info *wait)
 {
 	struct ieee80211_sta *sta = rtwsta_link_to_sta_safe(rtwsta_link);
 	struct ieee80211_vif *vif = rtwvif_link_to_vif(rtwvif_link);
+	struct rtw89_tx_skb_data *skb_data = RTW89_TX_SKB_CB(skb);
 	struct rtw89_vif *rtwvif = rtwvif_link->rtwvif;
 	struct rtw89_core_tx_request tx_req = {};
 	int ret;
@@ -1254,6 +1245,8 @@ static int rtw89_core_tx_write_link(struct rtw89_dev *rtwdev,
 	rtw89_core_tx_update_desc_info(rtwdev, &tx_req);
 	rtw89_core_tx_wake(rtwdev, &tx_req);
 
+	rcu_assign_pointer(skb_data->wait, wait);
+
 	ret = rtw89_hci_tx_write(rtwdev, &tx_req);
 	if (ret) {
 		rtw89_err(rtwdev, "failed to transmit skb to HCI\n");
@@ -1290,7 +1283,8 @@ int rtw89_core_tx_write(struct rtw89_dev *rtwdev, struct ieee80211_vif *vif,
 		}
 	}
 
-	return rtw89_core_tx_write_link(rtwdev, rtwvif_link, rtwsta_link, skb, qsel, false);
+	return rtw89_core_tx_write_link(rtwdev, rtwvif_link, rtwsta_link, skb, qsel, false,
+					NULL);
 }
 
 static __le32 rtw89_build_txwd_body0(struct rtw89_tx_desc_info *desc_info)
@@ -3928,6 +3922,7 @@ int rtw89_core_send_nullfunc(struct rtw89_dev *rtwdev, struct rtw89_vif_link *rt
 	struct ieee80211_vif *vif = rtwvif_link_to_vif(rtwvif_link);
 	int link_id = ieee80211_vif_is_mld(vif) ? rtwvif_link->link_id : -1;
 	struct rtw89_sta_link *rtwsta_link;
+	struct rtw89_tx_wait_info *wait;
 	struct ieee80211_sta *sta;
 	struct ieee80211_hdr *hdr;
 	struct rtw89_sta *rtwsta;
@@ -3937,6 +3932,12 @@ int rtw89_core_send_nullfunc(struct rtw89_dev *rtwdev, struct rtw89_vif_link *rt
 	if (vif->type != NL80211_IFTYPE_STATION || !vif->cfg.assoc)
 		return 0;
 
+	wait = kzalloc(sizeof(*wait), GFP_KERNEL);
+	if (!wait)
+		return -ENOMEM;
+
+	init_completion(&wait->completion);
+
 	rcu_read_lock();
 	sta = ieee80211_find_sta(vif, vif->cfg.ap_addr);
 	if (!sta) {
@@ -3951,6 +3952,8 @@ int rtw89_core_send_nullfunc(struct rtw89_dev *rtwdev, struct rtw89_vif_link *rt
 		goto out;
 	}
 
+	wait->skb = skb;
+
 	hdr = (struct ieee80211_hdr *)skb->data;
 	if (ps)
 		hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_PM);
@@ -3961,7 +3964,8 @@ int rtw89_core_send_nullfunc(struct rtw89_dev *rtwdev, struct rtw89_vif_link *rt
 		goto out;
 	}
 
-	ret = rtw89_core_tx_write_link(rtwdev, rtwvif_link, rtwsta_link, skb, &qsel, true);
+	ret = rtw89_core_tx_write_link(rtwdev, rtwvif_link, rtwsta_link, skb, &qsel, true,
+				       wait);
 	if (ret) {
 		rtw89_warn(rtwdev, "nullfunc transmit failed: %d\n", ret);
 		dev_kfree_skb_any(skb);
@@ -3970,10 +3974,11 @@ int rtw89_core_send_nullfunc(struct rtw89_dev *rtwdev, struct rtw89_vif_link *rt
 
 	rcu_read_unlock();
 
-	return rtw89_core_tx_kick_off_and_wait(rtwdev, skb, qsel,
+	return rtw89_core_tx_kick_off_and_wait(rtwdev, skb, wait, qsel,
 					       timeout);
 out:
 	rcu_read_unlock();
+	kfree(wait);
 
 	return ret;
 }
diff --git a/drivers/net/wireless/realtek/rtw89/core.h b/drivers/net/wireless/realtek/rtw89/core.h
index d15fa70eb4dc..928c8c84c964 100644
--- a/drivers/net/wireless/realtek/rtw89/core.h
+++ b/drivers/net/wireless/realtek/rtw89/core.h
@@ -7476,7 +7476,8 @@ int rtw89_h2c_tx(struct rtw89_dev *rtwdev,
 		 struct sk_buff *skb, bool fwdl);
 void rtw89_core_tx_kick_off(struct rtw89_dev *rtwdev, u8 qsel);
 int rtw89_core_tx_kick_off_and_wait(struct rtw89_dev *rtwdev, struct sk_buff *skb,
-				    int qsel, unsigned int timeout);
+				    struct rtw89_tx_wait_info *wait, int qsel,
+				    unsigned int timeout);
 void rtw89_core_fill_txdesc(struct rtw89_dev *rtwdev,
 			    struct rtw89_tx_desc_info *desc_info,
 			    void *txdesc);
diff --git a/drivers/net/wireless/realtek/rtw89/pci.c b/drivers/net/wireless/realtek/rtw89/pci.c
index 8dd91d867ea6..0ee5f8579447 100644
--- a/drivers/net/wireless/realtek/rtw89/pci.c
+++ b/drivers/net/wireless/realtek/rtw89/pci.c
@@ -1494,7 +1494,6 @@ static int rtw89_pci_txwd_submit(struct rtw89_dev *rtwdev,
 	struct pci_dev *pdev = rtwpci->pdev;
 	struct sk_buff *skb = tx_req->skb;
 	struct rtw89_pci_tx_data *tx_data = RTW89_PCI_TX_SKB_CB(skb);
-	struct rtw89_tx_skb_data *skb_data = RTW89_TX_SKB_CB(skb);
 	bool en_wd_info = desc_info->en_wd_info;
 	u32 txwd_len;
 	u32 txwp_len;
@@ -1510,7 +1509,6 @@ static int rtw89_pci_txwd_submit(struct rtw89_dev *rtwdev,
 	}
 
 	tx_data->dma = dma;
-	rcu_assign_pointer(skb_data->wait, NULL);
 
 	txwp_len = sizeof(*txwp_info);
 	txwd_len = chip->txwd_body_size;
-- 
2.51.0

[PATCH rtw-next v5 3/4] wifi: rtw89: fix leak in rtw89_core_send_nullfunc()

[Fedor Pchelkin]

If there is no rtwsta_link found in rtw89_core_send_nullfunc(), allocated
skb is leaked.  Free it on the error handling path.

Found by Linux Verification Center (linuxtesting.org).

Fixes: a8ba4acab7db ("wifi: rtw89: send nullfunc based on the given link")
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
---

v3: - use dev_kfree_skb_any() directly on error handling path without
      extra goto complexity  (Zong-Zhe)

 drivers/net/wireless/realtek/rtw89/core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/wireless/realtek/rtw89/core.c b/drivers/net/wireless/realtek/rtw89/core.c
index 1f44c7fc1c5e..917b2adede61 100644
--- a/drivers/net/wireless/realtek/rtw89/core.c
+++ b/drivers/net/wireless/realtek/rtw89/core.c
@@ -3961,6 +3961,7 @@ int rtw89_core_send_nullfunc(struct rtw89_dev *rtwdev, struct rtw89_vif_link *rt
 	rtwsta_link = rtwsta->links[rtwvif_link->link_id];
 	if (unlikely(!rtwsta_link)) {
 		ret = -ENOLINK;
+		dev_kfree_skb_any(skb);
 		goto out;
 	}
 
-- 
2.51.0

[PATCH rtw-next v5 4/4] wifi: rtw89: avoid circular locking dependency in ser_state_run()

[Fedor Pchelkin]

Lockdep gives a splat [1] when ser_hdl_work item is executed.  It is
scheduled at mac80211 workqueue via ieee80211_queue_work() and takes a
wiphy lock inside.  However, this workqueue can be flushed when e.g.
closing the interface and wiphy lock is already taken in that case.

Choosing wiphy_work_queue() for SER is likely not suitable.  Back on to
the global workqueue.

[1]:

 WARNING: possible circular locking dependency detected
 6.17.0-rc2 #17 Not tainted
 ------------------------------------------------------
 kworker/u32:1/61 is trying to acquire lock:
 ffff88811bc00768 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: ser_state_run+0x5e/0x180 [rtw89_core]

 but task is already holding lock:
 ffffc9000048fd30 ((work_completion)(&ser->ser_hdl_work)){+.+.}-{0:0}, at: process_one_work+0x7b5/0x1450

 which lock already depends on the new lock.

 the existing dependency chain (in reverse order) is:

 -> #2 ((work_completion)(&ser->ser_hdl_work)){+.+.}-{0:0}:
        process_one_work+0x7c6/0x1450
        worker_thread+0x49e/0xd00
        kthread+0x313/0x640
        ret_from_fork+0x221/0x300
        ret_from_fork_asm+0x1a/0x30

 -> #1 ((wq_completion)phy0){+.+.}-{0:0}:
        touch_wq_lockdep_map+0x8e/0x180
        __flush_workqueue+0x129/0x10d0
        ieee80211_stop_device+0xa8/0x110
        ieee80211_do_stop+0x14ce/0x2880
        ieee80211_stop+0x13a/0x2c0
        __dev_close_many+0x18f/0x510
        __dev_change_flags+0x25f/0x670
        netif_change_flags+0x7b/0x160
        do_setlink.isra.0+0x1640/0x35d0
        rtnl_newlink+0xd8c/0x1d30
        rtnetlink_rcv_msg+0x700/0xb80
        netlink_rcv_skb+0x11d/0x350
        netlink_unicast+0x49a/0x7a0
        netlink_sendmsg+0x759/0xc20
        ____sys_sendmsg+0x812/0xa00
        ___sys_sendmsg+0xf7/0x180
        __sys_sendmsg+0x11f/0x1b0
        do_syscall_64+0xbb/0x360
        entry_SYSCALL_64_after_hwframe+0x77/0x7f

 -> #0 (&rdev->wiphy.mtx){+.+.}-{4:4}:
        __lock_acquire+0x124c/0x1d20
        lock_acquire+0x154/0x2e0
        __mutex_lock+0x17b/0x12f0
        ser_state_run+0x5e/0x180 [rtw89_core]
        rtw89_ser_hdl_work+0x119/0x220 [rtw89_core]
        process_one_work+0x82d/0x1450
        worker_thread+0x49e/0xd00
        kthread+0x313/0x640
        ret_from_fork+0x221/0x300
        ret_from_fork_asm+0x1a/0x30

 other info that might help us debug this:

 Chain exists of:
   &rdev->wiphy.mtx --> (wq_completion)phy0 --> (work_completion)(&ser->ser_hdl_work)

  Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock((work_completion)(&ser->ser_hdl_work));
                                lock((wq_completion)phy0);
                                lock((work_completion)(&ser->ser_hdl_work));
   lock(&rdev->wiphy.mtx);

  *** DEADLOCK ***

 2 locks held by kworker/u32:1/61:
  #0: ffff888103835148 ((wq_completion)phy0){+.+.}-{0:0}, at: process_one_work+0xefa/0x1450
  #1: ffffc9000048fd30 ((work_completion)(&ser->ser_hdl_work)){+.+.}-{0:0}, at: process_one_work+0x7b5/0x1450

 stack backtrace:
 CPU: 0 UID: 0 PID: 61 Comm: kworker/u32:1 Not tainted 6.17.0-rc2 #17 PREEMPT(voluntary)
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS edk2-20250523-14.fc42 05/23/2025
 Workqueue: phy0 rtw89_ser_hdl_work [rtw89_core]
 Call Trace:
  <TASK>
  dump_stack_lvl+0x5d/0x80
  print_circular_bug.cold+0x178/0x1be
  check_noncircular+0x14c/0x170
  __lock_acquire+0x124c/0x1d20
  lock_acquire+0x154/0x2e0
  __mutex_lock+0x17b/0x12f0
  ser_state_run+0x5e/0x180 [rtw89_core]
  rtw89_ser_hdl_work+0x119/0x220 [rtw89_core]
  process_one_work+0x82d/0x1450
  worker_thread+0x49e/0xd00
  kthread+0x313/0x640
  ret_from_fork+0x221/0x300
  ret_from_fork_asm+0x1a/0x30
  </TASK>

Found by Linux Verification Center (linuxtesting.org).

Fixes: ebfc9199df05 ("wifi: rtw89: add wiphy_lock() to work that isn't held wiphy_lock() yet")
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
---
 drivers/net/wireless/realtek/rtw89/ser.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtw89/ser.c b/drivers/net/wireless/realtek/rtw89/ser.c
index fe7beff8c424..f99e179f7ff9 100644
--- a/drivers/net/wireless/realtek/rtw89/ser.c
+++ b/drivers/net/wireless/realtek/rtw89/ser.c
@@ -205,7 +205,6 @@ static void rtw89_ser_hdl_work(struct work_struct *work)
 
 static int ser_send_msg(struct rtw89_ser *ser, u8 event)
 {
-	struct rtw89_dev *rtwdev = container_of(ser, struct rtw89_dev, ser);
 	struct ser_msg *msg = NULL;
 
 	if (test_bit(RTW89_SER_DRV_STOP_RUN, ser->flags))
@@ -221,7 +220,7 @@ static int ser_send_msg(struct rtw89_ser *ser, u8 event)
 	list_add(&msg->list, &ser->msg_q);
 	spin_unlock_irq(&ser->msg_q_lock);
 
-	ieee80211_queue_work(rtwdev->hw, &ser->ser_hdl_work);
+	schedule_work(&ser->ser_hdl_work);
 	return 0;
 }
 
-- 
2.51.0

RE: [PATCH rtw-next v5 1/4] wifi: rtw89: fix use-after-free in rtw89_core_tx_kick_off_and_wait()

[Ping-Ke Shih]

Fedor Pchelkin <pchelkin@ispras.ru> wrote:
> There is a bug observed when rtw89_core_tx_kick_off_and_wait() tries to
> access already freed skb_data:
> 
>  BUG: KFENCE: use-after-free write in rtw89_core_tx_kick_off_and_wait
> drivers/net/wireless/realtek/rtw89/core.c:1110
> 
>  CPU: 6 UID: 0 PID: 41377 Comm: kworker/u64:24 Not tainted  6.17.0-rc1+ #1 PREEMPT(lazy)
>  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS edk2-20250523-14.fc42 05/23/2025
>  Workqueue: events_unbound cfg80211_wiphy_work [cfg80211]
> 
>  Use-after-free write at 0x0000000020309d9d (in kfence-#251):
>  rtw89_core_tx_kick_off_and_wait drivers/net/wireless/realtek/rtw89/core.c:1110
>  rtw89_core_scan_complete drivers/net/wireless/realtek/rtw89/core.c:5338
>  rtw89_hw_scan_complete_cb drivers/net/wireless/realtek/rtw89/fw.c:7979
>  rtw89_chanctx_proceed_cb drivers/net/wireless/realtek/rtw89/chan.c:3165
>  rtw89_chanctx_proceed drivers/net/wireless/realtek/rtw89/chan.h:141
>  rtw89_hw_scan_complete drivers/net/wireless/realtek/rtw89/fw.c:8012
>  rtw89_mac_c2h_scanofld_rsp drivers/net/wireless/realtek/rtw89/mac.c:5059
>  rtw89_fw_c2h_work drivers/net/wireless/realtek/rtw89/fw.c:6758
>  process_one_work kernel/workqueue.c:3241
>  worker_thread kernel/workqueue.c:3400
>  kthread kernel/kthread.c:463
>  ret_from_fork arch/x86/kernel/process.c:154
>  ret_from_fork_asm arch/x86/entry/entry_64.S:258
> 
>  kfence-#251: 0x0000000056e2393d-0x000000009943cb62, size=232, cache=skbuff_head_cache
> 
>  allocated by task 41377 on cpu 6 at 77869.159548s (0.009551s ago):
>  __alloc_skb net/core/skbuff.c:659
>  __netdev_alloc_skb net/core/skbuff.c:734
>  ieee80211_nullfunc_get net/mac80211/tx.c:5844
>  rtw89_core_send_nullfunc drivers/net/wireless/realtek/rtw89/core.c:3431
>  rtw89_core_scan_complete drivers/net/wireless/realtek/rtw89/core.c:5338
>  rtw89_hw_scan_complete_cb drivers/net/wireless/realtek/rtw89/fw.c:7979
>  rtw89_chanctx_proceed_cb drivers/net/wireless/realtek/rtw89/chan.c:3165
>  rtw89_chanctx_proceed drivers/net/wireless/realtek/rtw89/chan.c:3194
>  rtw89_hw_scan_complete drivers/net/wireless/realtek/rtw89/fw.c:8012
>  rtw89_mac_c2h_scanofld_rsp drivers/net/wireless/realtek/rtw89/mac.c:5059
>  rtw89_fw_c2h_work drivers/net/wireless/realtek/rtw89/fw.c:6758
>  process_one_work kernel/workqueue.c:3241
>  worker_thread kernel/workqueue.c:3400
>  kthread kernel/kthread.c:463
>  ret_from_fork arch/x86/kernel/process.c:154
>  ret_from_fork_asm arch/x86/entry/entry_64.S:258
> 
>  freed by task 1045 on cpu 9 at 77869.168393s (0.001557s ago):
>  ieee80211_tx_status_skb net/mac80211/status.c:1117
>  rtw89_pci_release_txwd_skb drivers/net/wireless/realtek/rtw89/pci.c:564
>  rtw89_pci_release_tx_skbs.isra.0 drivers/net/wireless/realtek/rtw89/pci.c:651
>  rtw89_pci_release_tx drivers/net/wireless/realtek/rtw89/pci.c:676
>  rtw89_pci_napi_poll drivers/net/wireless/realtek/rtw89/pci.c:4238
>  __napi_poll net/core/dev.c:7495
>  net_rx_action net/core/dev.c:7557 net/core/dev.c:7684
>  handle_softirqs kernel/softirq.c:580
>  do_softirq.part.0 kernel/softirq.c:480
>  __local_bh_enable_ip kernel/softirq.c:407
>  rtw89_pci_interrupt_threadfn drivers/net/wireless/realtek/rtw89/pci.c:927
>  irq_thread_fn kernel/irq/manage.c:1133
>  irq_thread kernel/irq/manage.c:1257
>  kthread kernel/kthread.c:463
>  ret_from_fork arch/x86/kernel/process.c:154
>  ret_from_fork_asm arch/x86/entry/entry_64.S:258
> 
> It is a consequence of a race between the waiting and the signaling side
> of the completion:
> 
>             Waiting thread                            Completing thread
> 
> rtw89_core_tx_kick_off_and_wait()
>   rcu_assign_pointer(skb_data->wait, wait)
>   /* start waiting */
>   wait_for_completion_timeout()
>                                                 rtw89_pci_tx_status()
>                                                   rtw89_core_tx_wait_complete()
>                                                     rcu_read_lock()
>                                                     /* signals completion and
>                                                      * proceeds further
>                                                      */
>                                                     complete(&wait->completion)
>                                                     rcu_read_unlock()
>                                                   ...
>                                                   /* frees skb_data */
>                                                   ieee80211_tx_status_ni()
>   /* returns (exit status doesn't matter) */
>   wait_for_completion_timeout()
>   ...
>   /* accesses the already freed skb_data */
>   rcu_assign_pointer(skb_data->wait, NULL)
> 
> The completing side might proceed and free the underlying skb even before
> the waiting side is fully awoken and run to execution.  Actually the race
> happens regardless of wait_for_completion_timeout() exit status, e.g.
> the waiting side may hit a timeout and the concurrent completing side is
> still able to free the skb.
> 
> Skbs which are sent by rtw89_core_tx_kick_off_and_wait() are owned by the
> driver.  They don't come from core ieee80211 stack so no need to pass them
> to ieee80211_tx_status_ni() on completing side.
> 
> Introduce a work function which will act as a garbage collector for
> rtw89_tx_wait_info objects and the associated skbs.  Thus no potentially
> heavy locks are required on the completing side.
> 
> Found by Linux Verification Center (linuxtesting.org).
> 
> Fixes: 1ae5ca615285 ("wifi: rtw89: add function to wait for completion of TX skbs")
> Cc: stable@vger.kernel.org
> Suggested-by: Zong-Zhe Yang <kevin_yang@realtek.com>
> Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>

Acked-by: Ping-Ke Shih <pkshih@realtek.com>

RE: [PATCH rtw-next v5 2/4] wifi: rtw89: avoid possible TX wait initialization race

[Ping-Ke Shih]

Fedor Pchelkin <pchelkin@ispras.ru> wrote:
> The value of skb_data->wait indicates whether skb is passed on to the
> core mac80211 stack or released by the driver itself.  Make sure that by
> the time skb is added to txwd queue and becomes visible to the completing
> side, it has already allocated and initialized TX wait related data (in
> case it's needed).
> 
> This is found by code review and addresses a possible race scenario
> described below:
> 
>       Waiting thread                          Completing thread
> 
> rtw89_core_send_nullfunc()
>   rtw89_core_tx_write_link()
>     ...
>     rtw89_pci_txwd_submit()
>       skb_data->wait = NULL
>       /* add skb to the queue */
>       skb_queue_tail(&txwd->queue, skb)
> 
>   /* another thread (e.g. rtw89_ops_tx) performs TX kick off for the same queue */
> 
>                                             rtw89_pci_napi_poll()
>                                             ...
>                                               rtw89_pci_release_txwd_skb()
>                                                 /* get skb from the queue */
>                                                 skb_unlink(skb, &txwd->queue)
>                                                 rtw89_pci_tx_status()
>                                                   rtw89_core_tx_wait_complete()
>                                                   /* use incorrect skb_data->wait */
>   rtw89_core_tx_kick_off_and_wait()
>   /* assign skb_data->wait but too late */
> 
> Found by Linux Verification Center (linuxtesting.org).
> 
> Fixes: 1ae5ca615285 ("wifi: rtw89: add function to wait for completion of TX skbs")
> Cc: stable@vger.kernel.org
> Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>

Acked-by: Ping-Ke Shih <pkshih@realtek.com>

Re: [PATCH rtw-next v5 1/4] wifi: rtw89: fix use-after-free in rtw89_core_tx_kick_off_and_wait()

[Ping-Ke Shih]

Fedor Pchelkin <pchelkin@ispras.ru> wrote:

> There is a bug observed when rtw89_core_tx_kick_off_and_wait() tries to
> access already freed skb_data:
> 
>  BUG: KFENCE: use-after-free write in rtw89_core_tx_kick_off_and_wait drivers/net/wireless/realtek/rtw89/core.c:1110
> 
>  CPU: 6 UID: 0 PID: 41377 Comm: kworker/u64:24 Not tainted  6.17.0-rc1+ #1 PREEMPT(lazy)
>  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS edk2-20250523-14.fc42 05/23/2025
>  Workqueue: events_unbound cfg80211_wiphy_work [cfg80211]
> 
>  Use-after-free write at 0x0000000020309d9d (in kfence-#251):
>  rtw89_core_tx_kick_off_and_wait drivers/net/wireless/realtek/rtw89/core.c:1110
>  rtw89_core_scan_complete drivers/net/wireless/realtek/rtw89/core.c:5338
>  rtw89_hw_scan_complete_cb drivers/net/wireless/realtek/rtw89/fw.c:7979
>  rtw89_chanctx_proceed_cb drivers/net/wireless/realtek/rtw89/chan.c:3165
>  rtw89_chanctx_proceed drivers/net/wireless/realtek/rtw89/chan.h:141
>  rtw89_hw_scan_complete drivers/net/wireless/realtek/rtw89/fw.c:8012
>  rtw89_mac_c2h_scanofld_rsp drivers/net/wireless/realtek/rtw89/mac.c:5059
>  rtw89_fw_c2h_work drivers/net/wireless/realtek/rtw89/fw.c:6758
>  process_one_work kernel/workqueue.c:3241
>  worker_thread kernel/workqueue.c:3400
>  kthread kernel/kthread.c:463
>  ret_from_fork arch/x86/kernel/process.c:154
>  ret_from_fork_asm arch/x86/entry/entry_64.S:258
> 
>  kfence-#251: 0x0000000056e2393d-0x000000009943cb62, size=232, cache=skbuff_head_cache
> 
>  allocated by task 41377 on cpu 6 at 77869.159548s (0.009551s ago):
>  __alloc_skb net/core/skbuff.c:659
>  __netdev_alloc_skb net/core/skbuff.c:734
>  ieee80211_nullfunc_get net/mac80211/tx.c:5844
>  rtw89_core_send_nullfunc drivers/net/wireless/realtek/rtw89/core.c:3431
>  rtw89_core_scan_complete drivers/net/wireless/realtek/rtw89/core.c:5338
>  rtw89_hw_scan_complete_cb drivers/net/wireless/realtek/rtw89/fw.c:7979
>  rtw89_chanctx_proceed_cb drivers/net/wireless/realtek/rtw89/chan.c:3165
>  rtw89_chanctx_proceed drivers/net/wireless/realtek/rtw89/chan.c:3194
>  rtw89_hw_scan_complete drivers/net/wireless/realtek/rtw89/fw.c:8012
>  rtw89_mac_c2h_scanofld_rsp drivers/net/wireless/realtek/rtw89/mac.c:5059
>  rtw89_fw_c2h_work drivers/net/wireless/realtek/rtw89/fw.c:6758
>  process_one_work kernel/workqueue.c:3241
>  worker_thread kernel/workqueue.c:3400
>  kthread kernel/kthread.c:463
>  ret_from_fork arch/x86/kernel/process.c:154
>  ret_from_fork_asm arch/x86/entry/entry_64.S:258
> 
>  freed by task 1045 on cpu 9 at 77869.168393s (0.001557s ago):
>  ieee80211_tx_status_skb net/mac80211/status.c:1117
>  rtw89_pci_release_txwd_skb drivers/net/wireless/realtek/rtw89/pci.c:564
>  rtw89_pci_release_tx_skbs.isra.0 drivers/net/wireless/realtek/rtw89/pci.c:651
>  rtw89_pci_release_tx drivers/net/wireless/realtek/rtw89/pci.c:676
>  rtw89_pci_napi_poll drivers/net/wireless/realtek/rtw89/pci.c:4238
>  __napi_poll net/core/dev.c:7495
>  net_rx_action net/core/dev.c:7557 net/core/dev.c:7684
>  handle_softirqs kernel/softirq.c:580
>  do_softirq.part.0 kernel/softirq.c:480
>  __local_bh_enable_ip kernel/softirq.c:407
>  rtw89_pci_interrupt_threadfn drivers/net/wireless/realtek/rtw89/pci.c:927
>  irq_thread_fn kernel/irq/manage.c:1133
>  irq_thread kernel/irq/manage.c:1257
>  kthread kernel/kthread.c:463
>  ret_from_fork arch/x86/kernel/process.c:154
>  ret_from_fork_asm arch/x86/entry/entry_64.S:258
> 
> It is a consequence of a race between the waiting and the signaling side
> of the completion:
> 
>             Waiting thread                            Completing thread
> 
> rtw89_core_tx_kick_off_and_wait()
>   rcu_assign_pointer(skb_data->wait, wait)
>   /* start waiting */
>   wait_for_completion_timeout()
>                                                 rtw89_pci_tx_status()
>                                                   rtw89_core_tx_wait_complete()
>                                                     rcu_read_lock()
>                                                     /* signals completion and
>                                                      * proceeds further
>                                                      */
>                                                     complete(&wait->completion)
>                                                     rcu_read_unlock()
>                                                   ...
>                                                   /* frees skb_data */
>                                                   ieee80211_tx_status_ni()
>   /* returns (exit status doesn't matter) */
>   wait_for_completion_timeout()
>   ...
>   /* accesses the already freed skb_data */
>   rcu_assign_pointer(skb_data->wait, NULL)
> 
> The completing side might proceed and free the underlying skb even before
> the waiting side is fully awoken and run to execution.  Actually the race
> happens regardless of wait_for_completion_timeout() exit status, e.g.
> the waiting side may hit a timeout and the concurrent completing side is
> still able to free the skb.
> 
> Skbs which are sent by rtw89_core_tx_kick_off_and_wait() are owned by the
> driver.  They don't come from core ieee80211 stack so no need to pass them
> to ieee80211_tx_status_ni() on completing side.
> 
> Introduce a work function which will act as a garbage collector for
> rtw89_tx_wait_info objects and the associated skbs.  Thus no potentially
> heavy locks are required on the completing side.
> 
> Found by Linux Verification Center (linuxtesting.org).
> 
> Fixes: 1ae5ca615285 ("wifi: rtw89: add function to wait for completion of TX skbs")
> Cc: stable@vger.kernel.org
> Suggested-by: Zong-Zhe Yang <kevin_yang@realtek.com>
> Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
> Acked-by: Ping-Ke Shih <pkshih@realtek.com>

4 patch(es) applied to rtw-next branch of rtw.git, thanks.

3e31a6bc0731 wifi: rtw89: fix use-after-free in rtw89_core_tx_kick_off_and_wait()
c24248ed78f3 wifi: rtw89: avoid possible TX wait initialization race
a9f0064f4716 wifi: rtw89: fix leak in rtw89_core_send_nullfunc()
570f94511766 wifi: rtw89: avoid circular locking dependency in ser_state_run()

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https://github.com/pkshih/rtw.git