[PATCH rtw-next v2] wifi: rtlwifi: pci: fix possible use-after-free caused by unfinished irq_prepare_bcn_tasklet

[Duoming Zhou]

The irq_prepare_bcn_tasklet is initialized in rtl_pci_init() and
scheduled when RTL_IMR_BCNINT interrupt is triggered by hardware.
But it is never killed in rtl_pci_deinit(). When the rtlwifi card
probe fails or is being detached, the ieee80211_hw is deallocated.
However, irq_prepare_bcn_tasklet may still be running or pending,
leading to use-after-free when the freed ieee80211_hw is accessed
in _rtl_pci_prepare_bcn_tasklet().

Similar to irq_tasklet, add tasklet_kill() in rtl_pci_deinit() to
ensure that irq_prepare_bcn_tasklet is properly terminated before
the ieee80211_hw is released.

The issue was identified through static analysis.

Fixes: 0c8173385e54 ("rtl8192ce: Add new driver")
Signed-off-by: Duoming Zhou <duoming@xxxxxxxxxx>
Acked-by: Ping-Ke Shih <pkshih@xxxxxxxxxxx>
---
Changes in v2:
  - Adjust the subject prefix and point out the problematic tasklet in subject.
  - Select the "rtw-next" tree.

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

diff --git a/drivers/net/wireless/realtek/rtlwifi/pci.c b/drivers/net/wireless/realtek/rtlwifi/pci.c
index d080469264c..f0010336e78 100644
--- a/drivers/net/wireless/realtek/rtlwifi/pci.c
+++ b/drivers/net/wireless/realtek/rtlwifi/pci.c
@@ -1674,6 +1674,7 @@ static void rtl_pci_deinit(struct ieee80211_hw *hw)
 
 	synchronize_irq(rtlpci->pdev->irq);
 	tasklet_kill(&rtlpriv->works.irq_tasklet);
+	tasklet_kill(&rtlpriv->works.irq_prepare_bcn_tasklet);
 	cancel_work_sync(&rtlpriv->works.lps_change_work);
 }
 
-- 
2.34.1