On 07/09/2021 21:01, 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
>
> 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().
>
> Cc: stable@xxxxxxxxxxxxxxx
> Suggested-by: David Collins <quic_collinsd@xxxxxxxxxxx>
> Signed-off-by: Subbaraman Narayanamurthy <quic_subbaram@xxxxxxxxxxx>
> ---
> Changes for v2:
> - Added checks in of_thermal_get_temp(), of_thermal_set_emul_temp(), of_thermal_get_trend().
>
> drivers/thermal/thermal_of.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/thermal/thermal_of.c b/drivers/thermal/thermal_of.c
> index 6379f26..9233f7e 100644
> --- a/drivers/thermal/thermal_of.c
> +++ b/drivers/thermal/thermal_of.c
> @@ -89,7 +89,7 @@ static int of_thermal_get_temp(struct thermal_zone_device *tz,
> {
> struct __thermal_zone *data = tz->devdata;
>
> - if (!data->ops->get_temp)
> + if (!data->ops || !data->ops->get_temp)
comment (1)
AFAICT, if data->ops != NULL then data->ops->get_temp is also != NULL
because of the code allocating/freeing the ops structure.
The tests can be replaced by (!data->ops), no ?
> return -EINVAL;
>
> return data->ops->get_temp(data->sensor_data, temp);
> @@ -186,6 +186,9 @@ static int of_thermal_set_emul_temp(struct thermal_zone_device *tz,
> {
> struct __thermal_zone *data = tz->devdata;
>
> + if (!data->ops || !data->ops->set_emul_temp)
> + return -EINVAL;
> +
comment (2)
The test looks pointless here (I mean both of them).
If of_thermal_set_emul_temp() is called it is because the callback was
set in thermal_zone_of_add_sensor().
This one does:
tz->ops = ops;
and
if (ops->set_emul_temp)
tzd->ops->set_emul_temp = of_thermal_set_emul_temp;
If I'm not wrong if we are called, then data->ops &&
data->ops->set_emul_temp is always true, right ?
> return data->ops->set_emul_temp(data->sensor_data, temp);
> }
>
> @@ -194,7 +197,7 @@ static int of_thermal_get_trend(struct thermal_zone_device *tz, int trip,
> {
> struct __thermal_zone *data = tz->devdata;
>
> - if (!data->ops->get_trend)
> + if (!data->ops || !data->ops->get_trend)
> return -EINVAL;
Same comment as (1)
> return data->ops->get_trend(data->sensor_data, trip, trend);
> @@ -301,7 +304,7 @@ 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) {
Same comment as (2)
> int ret;
>
> ret = data->ops->set_trip_temp(data->sensor_data, trip, temp);
>
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