On Fri, Jun 27, 2025 at 07:33:04AM +0200, Jiri Slaby wrote:
On 27. 06. 25, 0:47, Qasim Ijaz wrote:
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] ? input_attach_handler.isra.0+0x1a9/0x1e0 [ 63.192094] kasan_report+0xce/0x100 [ 63.192094] ? input_attach_handler.isra.0+0x1a9/0x1e0 [ 63.192094] input_attach_handler.isra.0+0x1a9/0x1e0 [ 63.192094] input_register_device+0x76c/0xd00 [ 63.192094] hidinput_connect+0x686d/0xad60 [ 63.192094] ? __pfx_hidinput_connect+0x10/0x10 [ 63.192094] ? xhci_urb_enqueue+0x523/0x930 [ 63.192094] hid_connect+0xf20/0x1b10 [ 63.192094] ? mutex_unlock+0x7d/0xd0 [ 63.192094] ? __pfx_mutex_unlock+0x10/0x10 [ 63.192094] ? __pm_runtime_idle+0x95/0x1c0 [ 63.192094] ? __pfx_hid_connect+0x10/0x10 [ 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] ? __pfx___device_attach_driver+0x10/0x10 [ 63.192094] bus_for_each_drv+0x10f/0x190 [ 63.192094] ? __pfx_bus_for_each_drv+0x10/0x10 [ 63.192094] __device_attach+0x18e/0x370 [ 63.192094] ? __pfx___device_attach+0x10/0x10 [ 63.192094] ? kobject_get+0x50/0xe0 [ 63.192094] bus_probe_device+0x123/0x170 [ 63.192094] device_add+0xd4d/0x1460 [ 63.192094] ? __pfx_device_add+0x10/0x10 [ 63.192094] ? up_write+0x4d/0x90 [ 63.192094] ? __debugfs_create_file+0x377/0x5a0 [ 63.192094] hid_add_device+0x30b/0x910 [ 63.192094] ? __pfx_hid_add_device+0x10/0x10 [ 63.192094] usbhid_probe+0x920/0xe00 [ 63.192094] ? pm_runtime_enable+0xfa/0x2a0 [ 63.192094] usb_probe_interface+0x363/0x9a0 [ 63.192094] ? sysfs_do_create_link_sd+0x89/0x100 [ 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] ? __pfx___device_attach_driver+0x10/0x10 [ 63.192094] bus_for_each_drv+0x10f/0x190 [ 63.192094] ? __pfx_bus_for_each_drv+0x10/0x10 [ 63.192094] __device_attach+0x18e/0x370 [ 63.192094] ? __pfx___device_attach+0x10/0x10 [ 63.192094] ? kobject_get+0x50/0xe0 [ 63.192094] bus_probe_device+0x123/0x170 [ 63.192094] device_add+0xd4d/0x1460 [ 63.192094] ? __pfx_device_add+0x10/0x10 [ 63.192094] ? mutex_unlock+0x7d/0xd0 [ 63.192094] ? __pfx_mutex_unlock+0x10/0x10 [ 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] ? usb_generic_driver_match+0x58/0x80 [ 63.192094] driver_probe_device+0x49/0x210 [ 63.192094] __device_attach_driver+0x160/0x320 [ 63.192094] ? __pfx___device_attach_driver+0x10/0x10 [ 63.192094] bus_for_each_drv+0x10f/0x190 [ 63.192094] ? __pfx_bus_for_each_drv+0x10/0x10 [ 63.192094] __device_attach+0x18e/0x370 [ 63.192094] ? __pfx___device_attach+0x10/0x10 [ 63.192094] ? kobject_get+0x50/0xe0 [ 63.192094] bus_probe_device+0x123/0x170 [ 63.192094] device_add+0xd4d/0x1460 [ 63.192094] ? __pfx_device_add+0x10/0x10 [ 63.192094] ? add_device_randomness+0xb2/0xe0 [ 63.192094] usb_new_device+0x7b4/0x1000 [ 63.192094] hub_event+0x234d/0x3fa0 [ 63.192094] ? __pfx_hub_event+0x10/0x10 [ 63.192094] ? _raw_spin_lock_irqsave+0x85/0xe0 [ 63.192094] ? _raw_spin_lock_irqsave+0x85/0xe0 [ 63.192094] ? mutex_unlock+0x7d/0xd0 [ 63.192094] ? _raw_spin_lock_irq+0x80/0xe0 [ 63.192094] ? __pfx__raw_spin_lock_irq+0x10/0x10 [ 63.192094] ? __pm_runtime_suspend+0x74/0x1c0 [ 63.192094] process_one_work+0x5bf/0xfe0 [ 63.192094] worker_thread+0x777/0x13a0 [ 63.192094] ? __kthread_parkme+0x99/0x180 [ 63.192094] ? __pfx_worker_thread+0x10/0x10 [ 63.192094] kthread+0x327/0x630 [ 63.192094] ? __pfx_kthread+0x10/0x10 [ 63.192094] ? __pfx__raw_spin_lock_irq+0x10/0x10 [ 63.192094] ? __pfx_kthread+0x10/0x10 [ 63.192094] ? __pfx_kthread+0x10/0x10 [ 63.192094] ret_from_fork+0xff/0x1a0 [ 63.192094] ? __pfx_kthread+0x10/0x10 [ 63.192094] ret_from_fork_asm+0x1a/0x30 [ 63.192094] </TASK>
If you are going to resend, could you prune that backtrace too? Like drop all '?' entries and everything after worker_thread.
good idea, will clean up the backtrace in v2.
Thanks, Qasim
thanks,
js suse labs