Re: [PATCH 1/6] wifi: mt76: mt7996: fix crash on some tx status reports

[Lorenzo Bianconi <lorenzo@kernel.org>]

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> When a wcid can't be found, link_sta can be stale from a previous batch.
> The code currently assumes that if link_sta is set, wcid is also non-zero.
> Fix wcid NULL pointer dereference by resetting link_sta when a wcid entry
> can't be found.
> 
> Fixes: 62da647a2b20 ("wifi: mt76: mt7996: Add MLO support to mt7996_tx_check_aggr()")

Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>

> Signed-off-by: Felix Fietkau <nbd@nbd.name>
> ---
>  drivers/net/wireless/mediatek/mt76/mt7996/mac.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/mediatek/mt76/mt7996/mac.c b/drivers/net/wireless/mediatek/mt76/mt7996/mac.c
> index d6531b74be1f..837deb41ae13 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt7996/mac.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt7996/mac.c
> @@ -1247,8 +1247,10 @@ mt7996_mac_tx_free(struct mt7996_dev *dev, void *data, int len)
>  			idx = FIELD_GET(MT_TXFREE_INFO_WLAN_ID, info);
>  			wcid = mt76_wcid_ptr(dev, idx);
>  			sta = wcid_to_sta(wcid);
> -			if (!sta)
> +			if (!sta) {
> +				link_sta = NULL;
>  				goto next;
> +			}
>  
>  			link_sta = rcu_dereference(sta->link[wcid->link_id]);
>  			if (!link_sta)
> -- 
> 2.51.0
> 
> 

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