usb: typec: ucsi: fix use-after-free caused by uec->work

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

usb: typec: ucsi: fix use-after-free caused by uec->work

The delayed work uec->work is scheduled in gaokun_ucsi_probe()

but never properly canceled in gaokun_ucsi_remove(). This creates

use-after-free scenarios where the ucsi and gaokun_ucsi structure

are freed after ucsi_destroy() completes execution, while the

gaokun_ucsi_register_worker() might be either currently executing

or still pending in the work queue. The already-freed gaokun_ucsi

or ucsi structure may then be accessed.

Furthermore, the race window is 3 seconds, which is sufficiently

long to make this bug easily reproducible. The following is the

trace captured by KASAN:

==================================================================

BUG: KASAN: slab-use-after-free in __run_timers+0x5ec/0x630

Write of size 8 at addr ffff00000ec28cc8 by task swapper/0/0

...

Call trace:

show_stack+0x18/0x24 (C)

dump_stack_lvl+0x78/0x90

print_report+0x114/0x580

kasan_report+0xa4/0xf0

__asan_report_store8_noabort+0x20/0x2c

__run_timers+0x5ec/0x630

run_timer_softirq+0xe8/0x1cc

handle_softirqs+0x294/0x720

__do_softirq+0x14/0x20

____do_softirq+0x10/0x1c

call_on_irq_stack+0x30/0x48

do_softirq_own_stack+0x1c/0x28

__irq_exit_rcu+0x27c/0x364

irq_exit_rcu+0x10/0x1c

el1_interrupt+0x40/0x60

el1h_64_irq_handler+0x18/0x24

el1h_64_irq+0x6c/0x70

arch_local_irq_enable+0x4/0x8 (P)

do_idle+0x334/0x458

cpu_startup_entry+0x60/0x70

rest_init+0x158/0x174

start_kernel+0x2f8/0x394

__primary_switched+0x8c/0x94

Allocated by task 72 on cpu 0 at 27.510341s:

kasan_save_stack+0x2c/0x54

kasan_save_track+0x24/0x5c

kasan_save_alloc_info+0x40/0x54

__kasan_kmalloc+0xa0/0xb8

__kmalloc_node_track_caller_noprof+0x1c0/0x588

devm_kmalloc+0x7c/0x1c8

gaokun_ucsi_probe+0xa0/0x840 auxiliary_bus_probe+0x94/0xf8

really_probe+0x17c/0x5b8

__driver_probe_device+0x158/0x2c4

driver_probe_device+0x10c/0x264

__device_attach_driver+0x168/0x2d0

bus_for_each_drv+0x100/0x188

__device_attach+0x174/0x368

device_initial_probe+0x14/0x20

bus_probe_device+0x120/0x150

device_add+0xb3c/0x10fc

__auxiliary_device_add+0x88/0x130

...

Freed by task 73 on cpu 1 at 28.910627s:

kasan_save_stack+0x2c/0x54

kasan_save_track+0x24/0x5c

__kasan_save_free_info+0x4c/0x74

__kasan_slab_free+0x60/0x8c

kfree+0xd4/0x410

devres_release_all+0x140/0x1f0

device_unbind_cleanup+0x20/0x190

device_release_driver_internal+0x344/0x460

device_release_driver+0x18/0x24

bus_remove_device+0x198/0x274

device_del+0x310/0xa84

...

The buggy address belongs to the object at ffff00000ec28c00

which belongs to the cache kmalloc-512 of size 512

The buggy address is located 200 bytes inside of

freed 512-byte region

The buggy address belongs to the physical page:

page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x4ec28

head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0

flags: 0x3fffe0000000040(head|node=0|zone=0|lastcpupid=0x1ffff)

page_type: f5(slab)

raw: 03fffe0000000040 ffff000008801c80 dead000000000122 0000000000000000

raw: 0000000000000000 0000000080100010 00000000f5000000 0000000000000000

head: 03fffe0000000040 ffff000008801c80 dead000000000122 0000000000000000

head: 0000000000000000 0000000080100010 00000000f5000000 0000000000000000

head: 03fffe0000000002 fffffdffc03b0a01 00000000ffffffff 00000000ffffffff

head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004

page dumped because: kasan: bad access detected

Memory state around the buggy address:

ffff00000ec28b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc

ffff00000ec28c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

>ffff00000ec28c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

^

ffff00000ec28d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

ffff00000ec28d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

================================================================

---truncated---