Describe CVE-2021-47268.
What is CVE-2021-47268?
In the Linux kernel, the following vulnerability has been resolved:

usb: typec: tcpm: cancel vdm and state machine hrtimer when unregister tcpm port

A pending hrtimer may expire after the kthread_worker of tcpm port
is destroyed, see below kernel dump when do module unload, fix it
by cancel the 2 hrtimers.

[  111.517018] Unable to handle kernel paging request at virtual address ffff8000118cb880
[  111.518786] blk_update_request: I/O error, dev sda, sector 60061185 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[  111.526594] Mem abort info:
[  111.526597]   ESR = 0x96000047
[  111.526600]   EC = 0x25: DABT (current EL), IL = 32 bits
[  111.526604]   SET = 0, FnV = 0
[  111.526607]   EA = 0, S1PTW = 0
[  111.526610] Data abort info:
[  111.526612]   ISV = 0, ISS = 0x00000047
[  111.526615]   CM = 0, WnR = 1
[  111.526619] swapper pgtable: 4k pages, 48-bit VAs, pgdp=0000000041d75000
[  111.526623] [ffff8000118cb880] pgd=10000001bffff003, p4d=10000001bffff003, pud=10000001bfffe003, pmd=10000001bfffa003, pte=0000000000000000
[  111.526642] Internal error: Oops: 96000047 [#1] PREEMPT SMP
[  111.526647] Modules linked in: dwc3_imx8mp dwc3 phy_fsl_imx8mq_usb [last unloaded: tcpci]
[  111.526663] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.13.0-rc4-00927-gebbe9dbd802c-dirty #36
[  111.526670] Hardware name: NXP i.MX8MPlus EVK board (DT)
[  111.526674] pstate: 800000c5 (Nzcv daIF -PAN -UAO -TCO BTYPE=--)
[  111.526681] pc : queued_spin_lock_slowpath+0x1a0/0x390
[  111.526695] lr : _raw_spin_lock_irqsave+0x88/0xb4
[  111.526703] sp : ffff800010003e20
[  111.526706] x29: ffff800010003e20 x28: ffff00017f380180
[  111.537156] buffer_io_error: 6 callbacks suppressed
[  111.537162] Buffer I/O error on dev sda1, logical block 60040704, async page read
[  111.539932]  x27: ffff00017f3801c0
[  111.539938] x26: ffff800010ba2490 x25: 0000000000000000 x24: 0000000000000001
[  111.543025] blk_update_request: I/O error, dev sda, sector 60061186 op 0x0:(READ) flags 0x0 phys_seg 7 prio class 0
[  111.548304]
[  111.548306] x23: 00000000000000c0 x22: ffff0000c2a9f184 x21: ffff00017f380180
[  111.551374] Buffer I/O error on dev sda1, logical block 60040705, async page read
[  111.554499]
[  111.554503] x20: ffff0000c5f14210 x19: 00000000000000c0 x18: 0000000000000000
[  111.557391] Buffer I/O error on dev sda1, logical block 60040706, async page read
[  111.561218]
[  111.561222] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
[  111.564205] Buffer I/O error on dev sda1, logical block 60040707, async page read
[  111.570887] x14: 00000000000000f5 x13: 0000000000000001 x12: 0000000000000040
[  111.570902] x11: ffff0000c05ac6d8
[  111.583420] Buffer I/O error on dev sda1, logical block 60040708, async page read
[  111.588978]  x10: 0000000000000000 x9 : 0000000000040000
[  111.588988] x8 : 0000000000000000
[  111.597173] Buffer I/O error on dev sda1, logical block 60040709, async page read
[  111.605766]  x7 : ffff00017f384880 x6 : ffff8000118cb880
[  111.605777] x5 : ffff00017f384880
[  111.611094] Buffer I/O error on dev sda1, logical block 60040710, async page read
[  111.617086]  x4 : 0000000000000000 x3 : ffff0000c2a9f184
[  111.617096] x2 : ffff8000118cb880
[  111.622242] Buffer I/O error on dev sda1, logical block 60040711, async page read
[  111.626927]  x1 : ffff8000118cb880 x0 : ffff00017f384888
[  111.626938] Call trace:
[  111.626942]  queued_spin_lock_slowpath+0x1a0/0x390
[  111.795809]  kthread_queue_work+0x30/0xc0
[  111.799828]  state_machine_timer_handler+0x20/0x30
[  111.804624]  __hrtimer_run_queues+0x140/0x1e0
[  111.808990]  hrtimer_interrupt+0xec/0x2c0
[  111.813004]  arch_timer_handler_phys+0x38/0x50
[  111.817456]  handle_percpu_devid_irq+0x88/0x150
[  111.821991]  __handle_domain_irq+0x80/0xe0
[  111.826093]  gic_handle_irq+0xc0/0x140
[  111.829848]  el1_irq+0xbc/0x154
[  111.832991]  arch_cpu_idle+0x1c/0x2c
[  111.836572]  default_idle_call+0x24/0x6c
[  111.840497]  do_idle+0x238/0x2ac
[  1
---truncated---.