HID: appletb-kbd: fix memory corruption of input_handler_list

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

HID: appletb-kbd: fix memory corruption of input_handler_list

In appletb_kbd_probe an input handler is initialised and then registered

with input core through input_register_handler(). When this happens input

core will add the input handler (specifically its node) to the global

input_handler_list. The input_handler_list is central to the functionality

of input core and is traversed in various places in input core. An example

of this is when a new input device is plugged in and gets registered with

input core.

The input_handler in probe is allocated as device managed memory. If a

probe failure occurs after input_register_handler() the input_handler

memory is freed, yet it will remain in the input_handler_list. This

effectively means the input_handler_list contains a dangling pointer

to data belonging to a freed input handler.

This causes an issue when any other input device is plugged in - in my

case I had an old PixArt HP USB optical mouse and I decided to

plug it in after a failure occurred after input_register_handler().

This lead to the registration of this input device via

input_register_device which involves traversing over every handler

in the corrupted input_handler_list and calling input_attach_handler(),

giving each handler a chance to bind to newly registered device.

The core of this bug is a UAF which causes memory corruption of

input_handler_list and to fix it we must ensure the input handler is

unregistered from input core, this is done through

input_unregister_handler().

[ 63.191597] ==================================================================

[ 63.192094] BUG: KASAN: slab-use-after-free in input_attach_handler.isra.0+0x1a9/0x1e0

[ 63.192094] Read of size 8 at addr ffff888105ea7c80 by task kworker/0:2/54

[ 63.192094]

[ 63.192094] CPU: 0 UID: 0 PID: 54 Comm: kworker/0:2 Not tainted 6.16.0-rc2-00321-g2aa6621d

[ 63.192094] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.164

[ 63.192094] Workqueue: usb_hub_wq hub_event

[ 63.192094] Call Trace:

[ 63.192094] <TASK>

[ 63.192094] dump_stack_lvl+0x53/0x70

[ 63.192094] print_report+0xce/0x670

[ 63.192094] kasan_report+0xce/0x100

[ 63.192094] input_attach_handler.isra.0+0x1a9/0x1e0

[ 63.192094] input_register_device+0x76c/0xd00

[ 63.192094] hidinput_connect+0x686d/0xad60

[ 63.192094] hid_connect+0xf20/0x1b10

[ 63.192094] hid_hw_start+0x83/0x100

[ 63.192094] hid_device_probe+0x2d1/0x680

[ 63.192094] really_probe+0x1c3/0x690

[ 63.192094] __driver_probe_device+0x247/0x300

[ 63.192094] driver_probe_device+0x49/0x210

[ 63.192094] __device_attach_driver+0x160/0x320

[ 63.192094] bus_for_each_drv+0x10f/0x190

[ 63.192094] __device_attach+0x18e/0x370

[ 63.192094] bus_probe_device+0x123/0x170

[ 63.192094] device_add+0xd4d/0x1460

[ 63.192094] hid_add_device+0x30b/0x910

[ 63.192094] usbhid_probe+0x920/0xe00

[ 63.192094] usb_probe_interface+0x363/0x9a0

[ 63.192094] really_probe+0x1c3/0x690

[ 63.192094] __driver_probe_device+0x247/0x300

[ 63.192094] driver_probe_device+0x49/0x210

[ 63.192094] __device_attach_driver+0x160/0x320

[ 63.192094] bus_for_each_drv+0x10f/0x190

[ 63.192094] __device_attach+0x18e/0x370

[ 63.192094] bus_probe_device+0x123/0x170

[ 63.192094] device_add+0xd4d/0x1460

[ 63.192094] usb_set_configuration+0xd14/0x1880

[ 63.192094] usb_generic_driver_probe+0x78/0xb0

[ 63.192094] usb_probe_device+0xaa/0x2e0

[ 63.192094] really_probe+0x1c3/0x690

[ 63.192094] __driver_probe_device+0x247/0x300

[ 63.192094] driver_probe_device+0x49/0x210

[ 63.192094] __device_attach_driver+0x160/0x320

[ 63.192094] bus_for_each_drv+0x10f/0x190

[ 63.192094] __device_attach+0x18e/0x370

[ 63.192094] bus_probe_device+0x123/0x170

[ 63.192094] device_add+0xd4d/0x1460

[ 63.192094] usb_new_device+0x7b4/0x1000

[ 63.192094] hub_event+0x234d/0x3

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