[PATCH 5.16 049/164] hwmon: Handle failure to register sensor with thermal zone correctly

Greg Kroah-Hartman
2022-02-28T18:04:08Z

From: Guenter Roeck <linux@roeck-us.net>

commit 1b5f517cca36292076d9e38fa6e33a257703e62e upstream.

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@nvidia.com>
Cc: Dmitry Osipenko <digetx@gmail.com>
Fixes: 1597b374af222 ("hwmon: Add notification support")
Reviewed-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/hwmon/hwmon.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)

--- a/drivers/hwmon/hwmon.c
+++ b/drivers/hwmon/hwmon.c
@@ -214,12 +214,14 @@ static int hwmon_thermal_add_sensor(stru

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)