CVE-2024-40912

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

wifi: mac80211: Fix deadlock in ieee80211_sta_ps_deliver_wakeup()

The ieee80211_sta_ps_deliver_wakeup() function takes sta->ps_lock to

synchronizes with ieee80211_tx_h_unicast_ps_buf() which is called from

softirq context. However using only spin_lock() to get sta->ps_lock in

ieee80211_sta_ps_deliver_wakeup() does not prevent softirq to execute

on this same CPU, to run ieee80211_tx_h_unicast_ps_buf() and try to

take this same lock ending in deadlock. Below is an example of rcu stall

that arises in such situation.

rcu: INFO: rcu_sched self-detected stall on CPU

rcu: 2-....: (42413413 ticks this GP) idle=b154/1/0x4000000000000000 softirq=1763/1765 fqs=21206996

rcu: (t=42586894 jiffies g=2057 q=362405 ncpus=4)

CPU: 2 PID: 719 Comm: wpa_supplicant Tainted: G W 6.4.0-02158-g1b062f552873 #742

Hardware name: RPT (r1) (DT)

pstate: 00000005 (nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)

pc : queued_spin_lock_slowpath+0x58/0x2d0

lr : invoke_tx_handlers_early+0x5b4/0x5c0

sp : ffff00001ef64660

x29: ffff00001ef64660 x28: ffff000009bc1070 x27: ffff000009bc0ad8

x26: ffff000009bc0900 x25: ffff00001ef647a8 x24: 0000000000000000

x23: ffff000009bc0900 x22: ffff000009bc0900 x21: ffff00000ac0e000

x20: ffff00000a279e00 x19: ffff00001ef646e8 x18: 0000000000000000

x17: ffff800016468000 x16: ffff00001ef608c0 x15: 0010533c93f64f80

x14: 0010395c9faa3946 x13: 0000000000000000 x12: 00000000fa83b2da

x11: 000000012edeceea x10: ffff0000010fbe00 x9 : 0000000000895440

x8 : 000000000010533c x7 : ffff00000ad8b740 x6 : ffff00000c350880

x5 : 0000000000000007 x4 : 0000000000000001 x3 : 0000000000000000

x2 : 0000000000000000 x1 : 0000000000000001 x0 : ffff00000ac0e0e8

Call trace:

queued_spin_lock_slowpath+0x58/0x2d0

ieee80211_tx+0x80/0x12c

ieee80211_tx_pending+0x110/0x278

tasklet_action_common.constprop.0+0x10c/0x144

tasklet_action+0x20/0x28

_stext+0x11c/0x284

____do_softirq+0xc/0x14

call_on_irq_stack+0x24/0x34

do_softirq_own_stack+0x18/0x20

do_softirq+0x74/0x7c

__local_bh_enable_ip+0xa0/0xa4

_ieee80211_wake_txqs+0x3b0/0x4b8

__ieee80211_wake_queue+0x12c/0x168

ieee80211_add_pending_skbs+0xec/0x138

ieee80211_sta_ps_deliver_wakeup+0x2a4/0x480

ieee80211_mps_sta_status_update.part.0+0xd8/0x11c

ieee80211_mps_sta_status_update+0x18/0x24

sta_apply_parameters+0x3bc/0x4c0

ieee80211_change_station+0x1b8/0x2dc

nl80211_set_station+0x444/0x49c

genl_family_rcv_msg_doit.isra.0+0xa4/0xfc

genl_rcv_msg+0x1b0/0x244

netlink_rcv_skb+0x38/0x10c

genl_rcv+0x34/0x48

netlink_unicast+0x254/0x2bc

netlink_sendmsg+0x190/0x3b4

____sys_sendmsg+0x1e8/0x218

___sys_sendmsg+0x68/0x8c

__sys_sendmsg+0x44/0x84

__arm64_sys_sendmsg+0x20/0x28

do_el0_svc+0x6c/0xe8

el0_svc+0x14/0x48

el0t_64_sync_handler+0xb0/0xb4

el0t_64_sync+0x14c/0x150

Using spin_lock_bh()/spin_unlock_bh() instead prevents softirq to raise

on the same CPU that is holding the lock.