[PATCH 6.12 079/567] hwmon: (ibmpex) fix use-after-free in high/low store

Greg Kroah-Hartman
2026-01-06T17:18:33Z

From: Junrui Luo <moonafterrain@outlook.com>

[ Upstream commit 6946c726c3f4c36f0f049e6f97e88c510b15f65d ]

The ibmpex_high_low_store() function retrieves driver data using
dev_get_drvdata() and uses it without validation. This creates a race
condition where the sysfs callback can be invoked after the data
structure is freed, leading to use-after-free.

Fix by adding a NULL check after dev_get_drvdata(), and reordering
operations in the deletion path to prevent TOCTOU.

Reported-by: Yuhao Jiang <danisjiang@gmail.com>
Reported-by: Junrui Luo <moonafterrain@outlook.com>
Fixes: 57c7c3a0fdea ("hwmon: IBM power meter driver")
Signed-off-by: Junrui Luo <moonafterrain@outlook.com>
Link: https://lore.kernel.org/r/MEYPR01MB7886BE2F51BFE41875B74B60AFA0A@MEYPR01MB7886.ausprd01.prod.outlook.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/hwmon/ibmpex.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/ibmpex.c b/drivers/hwmon/ibmpex.c
index 228c5f6c6f38..129f3a9e8fe9 100644
--- a/drivers/hwmon/ibmpex.c
+++ b/drivers/hwmon/ibmpex.c
@@ -277,6 +277,9 @@ static ssize_t ibmpex_high_low_store(struct device *dev,
{
struct ibmpex_bmc_data *data = dev_get_drvdata(dev);

+ if (!data)
+ return -ENODEV;
+
ibmpex_reset_high_low_data(data);

return count;
@@ -508,6 +511,9 @@ static void ibmpex_bmc_delete(struct ibmpex_bmc_data *data)
{
int i, j;

+ hwmon_device_unregister(data->hwmon_dev);
+ dev_set_drvdata(data->bmc_device, NULL);
+
device_remove_file(data->bmc_device,
&sensor_dev_attr_reset_high_low.dev_attr);
device_remove_file(data->bmc_device, &dev_attr_name.attr);
@@ -521,8 +527,7 @@ static void ibmpex_bmc_delete(struct ibmpex_bmc_data *data)
}

list_del(&data->list);
- dev_set_drvdata(data->bmc_device, NULL);
- hwmon_device_unregister(data->hwmon_dev);
+
ipmi_destroy_user(data->user);
kfree(data->sensors);
kfree(data);
--
2.51.0