wifi: ar5523: Fix use-after-free on ar5523_cmd() timed out
CVE: CVE-2022-50716
Component: kernel
Severity: None
Release date: 2022-01-01T00:00:00+00:00

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

wifi: ar5523: Fix use-after-free on ar5523_cmd() timed out

syzkaller reported use-after-free with the stack trace like below [1]:

[   38.960489][    C3] ==================================================================
[   38.963216][    C3] BUG: KASAN: use-after-free in ar5523_cmd_tx_cb+0x220/0x240
[   38.964950][    C3] Read of size 8 at addr ffff888048e03450 by task swapper/3/0
[   38.966363][    C3]
[   38.967053][    C3] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 6.0.0-09039-ga6afa4199d3d-dirty #18
[   38.968464][    C3] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-1.fc36 04/01/2014
[   38.969959][    C3] Call Trace:
[   38.970841][    C3]  <IRQ>
[   38.971663][    C3]  dump_stack_lvl+0xfc/0x174
[   38.972620][    C3]  print_report.cold+0x2c3/0x752
[   38.973626][    C3]  ? ar5523_cmd_tx_cb+0x220/0x240
[   38.974644][    C3]  kasan_report+0xb1/0x1d0
[   38.975720][    C3]  ? ar5523_cmd_tx_cb+0x220/0x240
[   38.976831][    C3]  ar5523_cmd_tx_cb+0x220/0x240
[   38.978412][    C3]  __usb_hcd_giveback_urb+0x353/0x5b0
[   38.979755][    C3]  usb_hcd_giveback_urb+0x385/0x430
[   38.981266][    C3]  dummy_timer+0x140c/0x34e0
[   38.982925][    C3]  ? notifier_call_chain+0xb5/0x1e0
[   38.984761][    C3]  ? rcu_read_lock_sched_held+0xb/0x60
[   38.986242][    C3]  ? lock_release+0x51c/0x790
[   38.987323][    C3]  ? _raw_read_unlock_irqrestore+0x37/0x70
[   38.988483][    C3]  ? __wake_up_common_lock+0xde/0x130
[   38.989621][    C3]  ? reacquire_held_locks+0x4a0/0x4a0
[   38.990777][    C3]  ? lock_acquire+0x472/0x550
[   38.991919][    C3]  ? rcu_read_lock_sched_held+0xb/0x60
[   38.993138][    C3]  ? lock_acquire+0x472/0x550
[   38.994890][    C3]  ? dummy_urb_enqueue+0x860/0x860
[   38.996266][    C3]  ? do_raw_spin_unlock+0x16f/0x230
[   38.997670][    C3]  ? dummy_urb_enqueue+0x860/0x860
[   38.999116][    C3]  call_timer_fn+0x1a0/0x6a0
[   39.000668][    C3]  ? add_timer_on+0x4a0/0x4a0
[   39.002137][    C3]  ? reacquire_held_locks+0x4a0/0x4a0
[   39.003809][    C3]  ? __next_timer_interrupt+0x226/0x2a0
[   39.005509][    C3]  __run_timers.part.0+0x69a/0xac0
[   39.007025][    C3]  ? dummy_urb_enqueue+0x860/0x860
[   39.008716][    C3]  ? call_timer_fn+0x6a0/0x6a0
[   39.010254][    C3]  ? cpuacct_percpu_seq_show+0x10/0x10
[   39.011795][    C3]  ? kvm_sched_clock_read+0x14/0x40
[   39.013277][    C3]  ? sched_clock_cpu+0x69/0x2b0
[   39.014724][    C3]  run_timer_softirq+0xb6/0x1d0
[   39.016196][    C3]  __do_softirq+0x1d2/0x9be
[   39.017616][    C3]  __irq_exit_rcu+0xeb/0x190
[   39.019004][    C3]  irq_exit_rcu+0x5/0x20
[   39.020361][    C3]  sysvec_apic_timer_interrupt+0x8f/0xb0
[   39.021965][    C3]  </IRQ>
[   39.023237][    C3]  <TASK>

In ar5523_probe(), ar5523_host_available() calls ar5523_cmd() as below
(there are other functions which finally call ar5523_cmd()):

ar5523_probe()
-> ar5523_host_available()
   -> ar5523_cmd_read()
      -> ar5523_cmd()

If ar5523_cmd() timed out, then ar5523_host_available() failed and
ar5523_probe() freed the device structure.  So, ar5523_cmd_tx_cb()
might touch the freed structure.

This patch fixes this issue by canceling in-flight tx cmd if submitted
urb timed out.


Remediation: