[PATCH] thermal: Fix a NULL pointer dereference

[PATCH] thermal: Fix a NULL pointer dereference

[Subbaraman Narayanamurthy]

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

Cc: stable@vger.kernel.org
Suggested-by: David Collins <quic_collinsd@quicinc.com>
Signed-off-by: Subbaraman Narayanamurthy <quic_subbaram@quicinc.com>
---
 drivers/thermal/thermal_of.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/thermal/thermal_of.c b/drivers/thermal/thermal_of.c
index 6379f26..ba53252 100644
--- a/drivers/thermal/thermal_of.c
+++ b/drivers/thermal/thermal_of.c
@@ -301,7 +301,7 @@ static int of_thermal_set_trip_temp(struct thermal_zone_device *tz, int trip,
 	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);
-- 
2.7.4

Re: [PATCH] thermal: Fix a NULL pointer dereference

[David Collins]

On 9/3/21 5:34 PM, Subbaraman Narayanamurthy wrote:
> 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
> 
> Cc: stable@vger.kernel.org
> Suggested-by: David Collins <quic_collinsd@quicinc.com>
> Signed-off-by: Subbaraman Narayanamurthy <quic_subbaram@quicinc.com>
> ---
>   drivers/thermal/thermal_of.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/thermal/thermal_of.c b/drivers/thermal/thermal_of.c
> index 6379f26..ba53252 100644
> --- a/drivers/thermal/thermal_of.c
> +++ b/drivers/thermal/thermal_of.c
> @@ -301,7 +301,7 @@ static int of_thermal_set_trip_temp(struct thermal_zone_device *tz, int trip,
>   	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);
> 

It looks like the same kind of data->ops null pointer dereference issue is 
present in three other functions within this file: of_thermal_get_temp(), 
of_thermal_set_emul_temp(), and of_thermal_get_trend().  Should those be 
fixed along with of_thermal_set_trip_temp() in a single patch?

Thanks,
David

Re: [PATCH] thermal: Fix a NULL pointer dereference

[Subbaraman Narayanamurthy]

On 9/3/21 6:07 PM, David Collins wrote:
> On 9/3/21 5:34 PM, Subbaraman Narayanamurthy wrote:
>> 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
>>
>> Cc: stable@vger.kernel.org
>> Suggested-by: David Collins <quic_collinsd@quicinc.com>
>> Signed-off-by: Subbaraman Narayanamurthy <quic_subbaram@quicinc.com>
>> ---
>>   drivers/thermal/thermal_of.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/thermal/thermal_of.c b/drivers/thermal/thermal_of.c
>> index 6379f26..ba53252 100644
>> --- a/drivers/thermal/thermal_of.c
>> +++ b/drivers/thermal/thermal_of.c
>> @@ -301,7 +301,7 @@ static int of_thermal_set_trip_temp(struct thermal_zone_device *tz, int trip,
>>       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);
>>
>
> It looks like the same kind of data->ops null pointer dereference issue is present in three other functions within this file: of_thermal_get_temp(), of_thermal_set_emul_temp(), and of_thermal_get_trend().  Should those be fixed along with of_thermal_set_trip_temp() in a single patch?

Sure, I can make those changes in this patch itself.

>
> Thanks,
> David