hwmon: (fschmd) Fix a memleak on multiple opens of /dev/watchdog

commit c453615f77aa51593c1c9c9031b4278797d3fd19 upstream.

When /dev/watchdog gets opened a second time we return -EBUSY, but
we already have got a kref then, so we end up leaking our data struct.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/hwmon/fschmd.c b/drivers/hwmon/fschmd.c
index da1b1f9488afc335c60b1833ee3fb7d89d3b832d..f600813e2b65ffa1833f467913d59ad9799ef6a0 100644 (file)
--- a/drivers/hwmon/fschmd.c
+++ b/drivers/hwmon/fschmd.c
@@ -767,6 +767,7 @@ leave:
 static int watchdog_open(struct inode *inode, struct file *filp)
 {
        struct fschmd_data *pos, *data = NULL;
+       int watchdog_is_open;
 
        /* We get called from drivers/char/misc.c with misc_mtx hold, and we
           call misc_register() from fschmd_probe() with watchdog_data_mutex
@@ -781,10 +782,12 @@ static int watchdog_open(struct inode *inode, struct file *filp)
                }
        }
        /* Note we can never not have found data, so we don't check for this */
-       kref_get(&data->kref);
+       watchdog_is_open = test_and_set_bit(0, &data->watchdog_is_open);
+       if (!watchdog_is_open)
+               kref_get(&data->kref);
        mutex_unlock(&watchdog_data_mutex);
 
-       if (test_and_set_bit(0, &data->watchdog_is_open))
+       if (watchdog_is_open)
                return -EBUSY;
 
        /* Start the watchdog */