Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

wifi: mac80211: reset the AP_VLAN tailroom counter on ifdown

On ifup, AP_VLAN interfaces get crypto_tx_tailroom_needed_cnt from the AP interface, but it's never decremented again unless the AP is also brought down. Thus, bringing the same AP_VLAN up again will increment the counter again and eventually hit the sanity check:

WARN_ON_ONCE(sdata->crypto_tx_tailroom_needed_cnt != master->crypto_tx_tailroom_needed_cnt);

Reset it on ifdown to avoid that.