On 2/21/22 21:22, Guenter Roeck wrote:
> If an attempt is made to a sensor with a thermal zone and it fails,
> the call to devm_thermal_zone_of_sensor_register() may return -ENODEV.
> This may result in crashes similar to the following.
>
> Unable to handle kernel NULL pointer dereference at virtual address 00000000000003cd
> ...
> Internal error: Oops: 96000021 [#1] PREEMPT SMP
> ...
> pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> pc : mutex_lock+0x18/0x60
> lr : thermal_zone_device_update+0x40/0x2e0
> sp : ffff800014c4fc60
> x29: ffff800014c4fc60 x28: ffff365ee3f6e000 x27: ffffdde218426790
> x26: ffff365ee3f6e000 x25: 0000000000000000 x24: ffff365ee3f6e000
> x23: ffffdde218426870 x22: ffff365ee3f6e000 x21: 00000000000003cd
> x20: ffff365ee8bf3308 x19: ffffffffffffffed x18: 0000000000000000
> x17: ffffdde21842689c x16: ffffdde1cb7a0b7c x15: 0000000000000040
> x14: ffffdde21a4889a0 x13: 0000000000000228 x12: 0000000000000000
> x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000
> x8 : 0000000001120000 x7 : 0000000000000001 x6 : 0000000000000000
> x5 : 0068000878e20f07 x4 : 0000000000000000 x3 : 00000000000003cd
> x2 : ffff365ee3f6e000 x1 : 0000000000000000 x0 : 00000000000003cd
> Call trace:
> mutex_lock+0x18/0x60
> hwmon_notify_event+0xfc/0x110
> 0xffffdde1cb7a0a90
> 0xffffdde1cb7a0b7c
> irq_thread_fn+0x2c/0xa0
> irq_thread+0x134/0x240
> kthread+0x178/0x190
> ret_from_fork+0x10/0x20
> Code: d503201f d503201f d2800001 aa0103e4 (c8e47c02)
>
> Jon Hunter reports that the exact call sequence is:
>
> hwmon_notify_event()
> --> hwmon_thermal_notify()
> --> thermal_zone_device_update()
> --> update_temperature()
> --> mutex_lock()
>
> The hwmon core needs to handle all errors returned from calls
> to devm_thermal_zone_of_sensor_register(). If the call fails
> with -ENODEV, report that the sensor was not attached to a
> thermal zone but continue to register the hwmon device.
>
> Reported-by: Jon Hunter <jonathanh@xxxxxxxxxx>
> Cc: Dmitry Osipenko <digetx@xxxxxxxxx>
> Fixes: 1597b374af222 ("hwmon: Add notification support")
> Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> ---
> v2: Use dev_info instead of dev_warn, and change message to be
> less alarming.
>
> drivers/hwmon/hwmon.c | 14 ++++++++------
> 1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
> index 3501a3ead4ba..3ae961986fc3 100644
> --- a/drivers/hwmon/hwmon.c
> +++ b/drivers/hwmon/hwmon.c
> @@ -214,12 +214,14 @@ static int hwmon_thermal_add_sensor(struct device *dev, int index)
>
> tzd = devm_thermal_zone_of_sensor_register(dev, index, tdata,
> &hwmon_thermal_ops);
> - /*
> - * If CONFIG_THERMAL_OF is disabled, this returns -ENODEV,
> - * so ignore that error but forward any other error.
> - */
> - if (IS_ERR(tzd) && (PTR_ERR(tzd) != -ENODEV))
> - return PTR_ERR(tzd);
> + if (IS_ERR(tzd)) {
> + if (PTR_ERR(tzd) != -ENODEV)
> + return PTR_ERR(tzd);
> + dev_info(dev, "temp%d_input not attached to any thermal zone\n",
> + index + 1);
> + devm_kfree(dev, tdata);
> + return 0;
> + }
>
> err = devm_add_action(dev, hwmon_thermal_remove_sensor, &tdata->node);
> if (err)
LGTM, thank you. But still needs a t-b from Jon.
Reviewed-by: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx>
