diff options
| author | Benny Halevy <bhalevy@panasas.com> | 2007-05-15 11:15:27 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2007-07-12 16:34:31 -0700 |
| commit | 52f6b5e1f15fa8c06efa69a4b5faa69c04707c92 (patch) | |
| tree | 3918f4d76adad79172ce42de5691bfc8c4781d40 /drivers | |
| parent | efdff60885e36b5091cdc47742dd5768ff4119be (diff) | |
synchronization in usb_serial_put
I think there is a race between usb_serial_put() and
usb_serial_get_by_index() (and get_free_serial()) with regards
to handling the serial port refcount.
usb_serial_get_by_index() gets a reference on the serial port under
table_lock while return_serial releases all the returned ports
from the table under the same lock. However, the table_lock is not
taken around the call to kref_put, theoretically allowing to sneak
in and grab a reference after kref_put has already determined that
the reference count is zero (and before calling destroy_serial)
causing use after free.
Signed-off-by: Benny Halevy <bhalevy@ns1.bhalevy.com>
Cc: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/usb/serial/usb-serial.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c index e3e3728e16e..a3665659d13 100644 --- a/drivers/usb/serial/usb-serial.c +++ b/drivers/usb/serial/usb-serial.c @@ -122,11 +122,9 @@ static void return_serial(struct usb_serial *serial) if (serial == NULL) return; - spin_lock(&table_lock); for (i = 0; i < serial->num_ports; ++i) { serial_table[serial->minor + i] = NULL; } - spin_unlock(&table_lock); } static void destroy_serial(struct kref *kref) @@ -174,7 +172,9 @@ static void destroy_serial(struct kref *kref) void usb_serial_put(struct usb_serial *serial) { + spin_lock(&table_lock); kref_put(&serial->kref, destroy_serial); + spin_unlock(&table_lock); } /***************************************************************************** |