[PATCH 6.12 070/337] hwmon: (lm90) Only report alarms if driver is ready

6.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Guenter Roeck <[email protected]>

[ Upstream commit aa9429edf9fc0e90d6f4da19ea4b5495a54ab117 ]

Userspace can read sysfs attributes before driver registration is complete,
immediately after devm_hwmon_device_register_with_info() has been called.
At that time, data->hwmon_dev is not yet initialized. This can trigger
a NULL pointer access since lm90_update_device() and with it
lm90_update_alarms_locked() will be called. This call schedules
report_work and lm90_report_alarms(), which passes the still-NULL
data->hwmon_dev to hwmon_notify_event() and triggers a NULL pointer
dereference.

Fix the problem by only scheduling the report and alert workers
data->hwmon_dev is set.

Reported-by: Sashiko <[email protected]>
Fixes: f6d0775119fb9 ("hwmon: (lm90) Rework alarm/status handling")
Signed-off-by: Guenter Roeck <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
---
 drivers/hwmon/lm90.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
index 511d95a0efb36..45d5a2427dcb1 100644
--- a/drivers/hwmon/lm90.c
+++ b/drivers/hwmon/lm90.c
@@ -1149,7 +1149,7 @@ static int lm90_update_alarms_locked(struct lm90_data *data, bool force)
 		check_enable = (client->irq || !(data->config_orig & 0x80)) &&
 			(data->config & 0x80);
 
-		if (force || check_enable)
+		if (data->hwmon_dev && (force || check_enable))
 			schedule_work(&data->report_work);
 
 		/*
@@ -1157,7 +1157,7 @@ static int lm90_update_alarms_locked(struct lm90_data *data, bool force)
 		 * alarms are all clear, and alerts are currently disabled.
 		 * Otherwise (re)schedule worker if needed.
 		 */
-		if (check_enable) {
+		if (check_enable && data->hwmon_dev) {
 			if (!(data->current_alarms & data->alert_alarms)) {
 				dev_dbg(&client->dev, "Re-enabling ALERT#\n");
 				lm90_update_confreg(data, data->config & ~0x80);
-- 
2.53.0