In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211: refuse to make a monitor active when it has no queue A monitor interface only gets a TXQ if it's created active, and one can't be added later. Setting the flag on a down interface is still allowed, so the driver is handed a monitor with no queue. ath9k dereferences it: BUG: kernel NULL pointer dereference, address: 0000000000000066 RIP: 0010:ath_tx_node_init+0x49/0x170 [ath9k] ath9k_add_interface+0x10c/0x140 [ath9k] drv_add_interface+0x54/0x250 [mac80211] ieee80211_do_open+0x32f/0x800 [mac80211] Reached with CAP_NET_ADMIN by "iw dev X set monitor active" followed by "ip link set X up". RTNL is held, so netlink operations block behind it. Refuse the flag when there is no queue to give.
https://git.kernel.org/stable/c/b7b7d46ec4fa127767931938b282c361c0519af6
https://git.kernel.org/stable/c/abe15e643e576459469867758ae9c586a7bab95d
https://git.kernel.org/stable/c/46c223468537a05a404699771cd3e68532dab5e6
https://git.kernel.org/stable/c/2b04d6556964ae9f89819b86a0a7801e39c3aae5