CVE-2023-54288

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

wifi: mac80211: fortify the spinlock against deadlock by interrupt

In the function ieee80211_tx_dequeue() there is a particular locking
sequence:

begin:
spin_lock(&local->queue_stop_reason_lock);
q_stopped = local->queue_stop_reasons[q];
spin_unlock(&local->queue_stop_reason_lock);

However small the chance (increased by ftracetest), an asynchronous
interrupt can occur in between of spin_lock() and spin_unlock(),
and the interrupt routine will attempt to lock the same
&local->queue_stop_reason_lock again.

This will cause a costly reset of the CPU and the wifi device or an
altogether hang in the single CPU and single core scenario.

The only remaining spin_lock(&local->queue_stop_reason_lock) that
did not disable interrupts was patched, which should prevent any
deadlocks on the same CPU/core and the same wifi device.

This is the probable trace of the deadlock:

kernel: ================================
kernel: WARNING: inconsistent lock state
kernel: 6.3.0-rc6-mt-20230401-00001-gf86822a1170f #4 Tainted: G W
kernel: ——————————–
kernel: inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage.
kernel: kworker/5:0/25656 [HC0[0]:SC0[0]:HE1:SE1] takes:
kernel: ffff9d6190779478 (&local->queue_stop_reason_lock){+.?.}-{2:2}, at: return_to_handler+0x0/0x40
kernel: {IN-SOFTIRQ-W} state was registered at:
kernel: lock_acquire+0xc7/0x2d0
kernel: _raw_spin_lock+0x36/0x50
kernel: ieee80211_tx_dequeue+0xb4/0x1330 [mac80211]
kernel: iwl_mvm_mac_itxq_xmit+0xae/0x210 [iwlmvm]
kernel: iwl_mvm_mac_wake_tx_queue+0x2d/0xd0 [iwlmvm]
kernel: ieee80211_queue_skb+0x450/0x730 [mac80211]
kernel: __ieee80211_xmit_fast.constprop.66+0x834/0xa50 [mac80211]
kernel: __ieee80211_subif_start_xmit+0x217/0x530 [mac80211]
kernel: ieee80211_subif_start_xmit+0x60/0x580 [mac80211]
kernel: dev_hard_start_xmit+0xb5/0x260
kernel: __dev_queue_xmit+0xdbe/0x1200
kernel: neigh_resolve_output+0x166/0x260
kernel: ip_finish_output2+0x216/0xb80
kernel: __ip_finish_output+0x2a4/0x4d0
kernel: ip_finish_output+0x2d/0xd0
kernel: ip_output+0x82/0x2b0
kernel: ip_local_out+0xec/0x110
kernel: igmpv3_sendpack+0x5c/0x90
kernel: igmp_ifc_timer_expire+0x26e/0x4e0
kernel: call_timer_fn+0xa5/0x230
kernel: run_timer_softirq+0x27f/0x550
kernel: __do_softirq+0xb4/0x3a4
kernel: irq_exit_rcu+0x9b/0xc0
kernel: sysvec_apic_timer_interrupt+0x80/0xa0
kernel: asm_sysvec_apic_timer_interrupt+0x1f/0x30
kernel: _raw_spin_unlock_irqrestore+0x3f/0x70
kernel: free_to_partial_list+0x3d6/0x590
kernel: __slab_free+0x1b7/0x310
kernel: kmem_cache_free+0x52d/0x550
kernel: putname+0x5d/0x70
kernel: do_sys_openat2+0x1d7/0x310
kernel: do_sys_open+0x51/0x80
kernel: __x64_sys_openat+0x24/0x30
kernel: do_syscall_64+0x5c/0x90
kernel: entry_SYSCALL_64_after_hwframe+0x72/0xdc
kernel: irq event stamp: 5120729
kernel: hardirqs last enabled at (5120729): [] trace_graph_return+0xd6/0x120
kernel: hardirqs last disabled at (5120728): [] trace_graph_return+0xf0/0x120
kernel: softirqs last enabled at (5069900): [] return_to_handler+0x0/0x40
kernel: softirqs last disabled at (5067555): [] return_to_handler+0x0/0x40
kernel:
other info that might help us debug this:
kernel: Possible unsafe locking scenario:
kernel: CPU0
kernel: —-
kernel: lock(&local->queue_stop_reason_lock);
kernel:
kernel: lock(&local->queue_stop_reason_lock);
kernel:
*** DEADLOCK ***
kernel: 8 locks held by kworker/5:0/25656:
kernel: #0: ffff9d618009d138 ((wq_completion)events_freezable){+.+.}-{0:0}, at: process_one_work+0x1ca/0x530
kernel: #1: ffffb1ef4637fe68 ((work_completion)(&local->restart_work)){+.+.}-{0:0}, at: process_one_work+0x1ce/0x530
kernel: #2: ffffffff9f166548 (rtnl_mutex){+.+.}-{3:3}, at: return_to_handler+0x0/0x40
kernel: #3: ffff9d619
—truncated—