[PATCH 5.14 14/15] thermal: Fix NULL pointer dereferences in of_thermal_ functions

Greg Kroah-Hartman
2021-11-19T17:39:28Z

From: Subbaraman Narayanamurthy <quic_subbaram@quicinc.com>

commit 96cfe05051fd8543cdedd6807ec59a0e6c409195 upstream.

of_parse_thermal_zones() parses the thermal-zones node and registers a
thermal_zone device for each subnode. However, if a thermal zone is
consuming a thermal sensor and that thermal sensor device hasn't probed
yet, an attempt to set trip_point_*_temp for that thermal zone device
can cause a NULL pointer dereference. Fix it.

console:/sys/class/thermal/thermal_zone87 # echo 120000 > trip_point_0_temp
...
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000020
...
Call trace:
of_thermal_set_trip_temp+0x40/0xc4
trip_point_temp_store+0xc0/0x1dc
dev_attr_store+0x38/0x88
sysfs_kf_write+0x64/0xc0
kernfs_fop_write_iter+0x108/0x1d0
vfs_write+0x2f4/0x368
ksys_write+0x7c/0xec
__arm64_sys_write+0x20/0x30
el0_svc_common.llvm.7279915941325364641+0xbc/0x1bc
do_el0_svc+0x28/0xa0
el0_svc+0x14/0x24
el0_sync_handler+0x88/0xec
el0_sync+0x1c0/0x200

While at it, fix the possible NULL pointer dereference in other
functions as well: of_thermal_get_temp(), of_thermal_set_emul_temp(),
of_thermal_get_trend().

Suggested-by: David Collins <quic_collinsd@quicinc.com>
Signed-off-by: Subbaraman Narayanamurthy <quic_subbaram@quicinc.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/thermal/thermal_of.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

--- a/drivers/thermal/thermal_of.c
+++ b/drivers/thermal/thermal_of.c
@@ -89,7 +89,7 @@ static int of_thermal_get_temp(struct th
{
struct __thermal_zone *data = tz->devdata;

- if (!data->ops->get_temp)
+ if (!data->ops || !data->ops->get_temp)
return -EINVAL;

return data->ops->get_temp(data->sensor_data, temp);
@@ -186,6 +186,9 @@ static int of_thermal_set_emul_temp(stru
{
struct __thermal_zone *data = tz->devdata;

+ if (!data->ops || !data->ops->set_emul_temp)
+ return -EINVAL;
+
return data->ops->set_emul_temp(data->sensor_data, temp);
}

@@ -194,7 +197,7 @@ static int of_thermal_get_trend(struct t
{
struct __thermal_zone *data = tz->devdata;

- if (!data->ops->get_trend)
+ if (!data->ops || !data->ops->get_trend)
return -EINVAL;

return data->ops->get_trend(data->sensor_data, trip, trend);
@@ -301,7 +304,7 @@ static int of_thermal_set_trip_temp(stru
if (trip >= data->ntrips || trip < 0)
return -EDOM;

- if (data->ops->set_trip_temp) {
+ if (data->ops && data->ops->set_trip_temp) {
int ret;

ret = data->ops->set_trip_temp(data->sensor_data, trip, temp);