hwmon: (pmbus/ibm-cffps) Prevent writing on_off_config with bad data

If the user write parameters resulted in no bytes being written to the
temporary buffer, then ON_OFF_CONFIG will be written with uninitialized
data. Prevent this by bailing out in this case.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Link: https://lore.kernel.org/r/1578411640-16929-1-git-send-email-eajames@linux.ibm.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

diff --git a/drivers/hwmon/pmbus/ibm-cffps.c b/drivers/hwmon/pmbus/ibm-cffps.c
index 1c91ee1f9926611281627a5db2a2a007a0dde511..3795fe55b84fee866db49dcfea65962290ada075 100644 (file)
--- a/drivers/hwmon/pmbus/ibm-cffps.c
+++ b/drivers/hwmon/pmbus/ibm-cffps.c
@@ -250,7 +250,7 @@ static ssize_t ibm_cffps_debugfs_write(struct file *file,
                pmbus_set_page(psu->client, 0);
 
                rc = simple_write_to_buffer(&data, 1, ppos, buf, count);
-               if (rc < 0)
+               if (rc <= 0)
                        return rc;
 
                rc = i2c_smbus_write_byte_data(psu->client,