In this function, bf is guarded by an if statement, indicating that it may be NULL: if (bf && bf->bf_mpdu) {...} If bf is NULL, calling list_add_tail() may result in a null-pointer dereference: list_add_tail(&bf->list, &sc->beacon.bbuf); Therefore, add a defensive NULL check before invoking list_add_tail() to prevent this issue. Signed-off-by: Tuo Li --- drivers/net/wireless/ath/ath9k/beacon.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/net/wireless/ath/ath9k/beacon.c b/drivers/net/wireless/ath/ath9k/beacon.c index 4a27e3753c03..e39e2738ba1a 100644 --- a/drivers/net/wireless/ath/ath9k/beacon.c +++ b/drivers/net/wireless/ath/ath9k/beacon.c @@ -236,7 +236,8 @@ void ath9k_beacon_remove_slot(struct ath_softc *sc, struct ieee80211_vif *vif) avp->av_bcbuf = NULL; sc->beacon.bslot[avp->av_bslot] = NULL; - list_add_tail(&bf->list, &sc->beacon.bbuf); + if (bf) + list_add_tail(&bf->list, &sc->beacon.bbuf); tasklet_enable(&sc->bcon_tasklet); } -- 2.43.0