2025-07-25 12:53:39
Linux
PUBLISHED
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]