From 8bde3e395a85017f12af2b0ba5c3684f5af9c006 Mon Sep 17 00:00:00 2001 From: Guenter Roeck Date: Sat, 7 Feb 2026 08:12:25 -0800 Subject: [PATCH] Revert "hwmon: (ibmpex) fix use-after-free in high/low store" This reverts commit 6946c726c3f4c36f0f049e6f97e88c510b15f65d. Jean Delvare points out that the patch does not completely fix the reported problem, that it in fact introduces a (new) race condition, and that it may actually not be needed in the first place. Various AI reviews agree. Specific and relevant AI feedback: " This reordering sets the driver data to NULL before removing the sensor attributes in the loop below. ibmpex_show_sensor() retrieves this driver data via dev_get_drvdata() but does not check if it is NULL before dereferencing it to access data->sensors[]. If a userspace process reads a sensor file (like temp1_input) while this delete function is running, could it race with the dev_set_drvdata(..., NULL) call here and crash in ibmpex_show_sensor()? Would it be safer to keep the original order where device_remove_file() is called before clearing the driver data? device_remove_file() should wait for any active sysfs callbacks to complete, which might already prevent the use-after-free this patch intends to fix. " Revert the offending patch. If it can be shown that the originally reported alleged race condition does indeed exist, it can always be re-introduced with a complete fix. Reported-by: Jean Delvare Closes: https://lore.kernel.org/linux-hwmon/20260121095342.73e723cb@endymion/ Cc: Jean Delvare Cc: Junrui Luo Fixes: 6946c726c3f4 ("hwmon: (ibmpex) fix use-after-free in high/low store") Reviewed-by: Jean Delvare Signed-off-by: Guenter Roeck --- drivers/hwmon/ibmpex.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) diff --git a/drivers/hwmon/ibmpex.c b/drivers/hwmon/ibmpex.c index 129f3a9e8fe96..228c5f6c6f383 100644 --- a/drivers/hwmon/ibmpex.c +++ b/drivers/hwmon/ibmpex.c @@ -277,9 +277,6 @@ 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; @@ -511,9 +508,6 @@ 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); @@ -527,7 +521,8 @@ 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); -- 2.47.3