Re: [PATCH v1] HID: ft260: fix i2c probing for hwmon devices

[Jiri Kosina]

On Sat, 23 Oct 2021, Michael Zaidman wrote:

> The below scenario causes the kernel NULL pointer dereference failure:
> 1. sudo insmod hid-ft260.ko
> 2. sudo modprobe lm75
> 3. unplug USB hid-ft260
> 4. plug USB hid-ft260
> 
> [  +0.000006] Call Trace:
> [  +0.000004]  __i2c_smbus_xfer.part.0+0xd1/0x310
> [  +0.000007]  ? ft260_smbus_write+0x140/0x140 [hid_ft260]
> [  +0.000005]  __i2c_smbus_xfer+0x2b/0x80
> [  +0.000004]  i2c_smbus_xfer+0x61/0xf0
> [  +0.000005]  i2c_default_probe+0xf9/0x130
> [  +0.000004]  i2c_detect_address+0x84/0x160
> [  +0.000004]  ? kmem_cache_alloc_trace+0xf6/0x200
> [  +0.000009]  ? i2c_detect.isra.0+0x69/0x130
> [  +0.000005]  i2c_detect.isra.0+0xbf/0x130
> [  +0.000004]  ? __process_new_driver+0x30/0x30
> [  +0.000004]  __process_new_adapter+0x18/0x20
> [  +0.000004]  bus_for_each_drv+0x84/0xd0
> [  +0.000003]  i2c_register_adapter+0x1e4/0x400
> [  +0.000005]  i2c_add_adapter+0x5c/0x80
> [  +0.000004]  ft260_probe.cold+0x222/0x2e2 [hid_ft260]
> [  +0.000006]  hid_device_probe+0x10e/0x170 [hid]
> [  +0.000009]  really_probe+0xff/0x460
> [  +0.000004]  driver_probe_device+0xe9/0x160
> [  +0.000003]  __device_attach_driver+0x71/0xd0
> [  +0.000004]  ? driver_allows_async_probing+0x50/0x50
> [  +0.000004]  bus_for_each_drv+0x84/0xd0
> [  +0.000002]  __device_attach+0xde/0x1e0
> [  +0.000004]  device_initial_probe+0x13/0x20
> [  +0.000004]  bus_probe_device+0x8f/0xa0
> [  +0.000003]  device_add+0x333/0x5f0
> 
> It happened when i2c core probed for the devices associated with the lm75
> driver by invoking 2c_detect()-->..-->ft260_smbus_write() from within the
> ft260_probe before setting the adapter data with i2c_set_adapdata().
> 
> Moving the i2c_set_adapdata() before i2c_add_adapter() fixed the failure.
> 
> Signed-off-by: Michael Zaidman <michael.zaidman@xxxxxxxxx>
> Signed-off-by: Germain Hebert <germain.hebert@xxxxxxxxxx>

Applied, thanks.

-- 
Jiri Kosina
SUSE Labs