Function del_timer() does not guarantee that timer was really deleted.
If the timer handler is beeing executed at the moment, the function
does nothing. So, we have a race between del_timer() and kfree(), and
it's possible to use already freed memory in the handler.

This is compile-tested only. Please, consider applying or something like it.

[Should CC stable@ ?]

Signed-off-by: Kirill Tkhai <tk...@yandex.ru>
---
 drivers/media/usb/s2255/s2255drv.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/media/usb/s2255/s2255drv.c 
b/drivers/media/usb/s2255/s2255drv.c
index 1d4ba2b..503fd65 100644
--- a/drivers/media/usb/s2255/s2255drv.c
+++ b/drivers/media/usb/s2255/s2255drv.c
@@ -1522,7 +1522,7 @@ static void s2255_destroy(struct s2255_dev *dev)
        /* board shutdown stops the read pipe if it is running */
        s2255_board_shutdown(dev);
        /* make sure firmware still not trying to load */
-       del_timer(&dev->timer);  /* only started in .probe and .open */
+       del_timer_sync(&dev->timer);  /* only started in .probe and .open */
        if (dev->fw_data->fw_urb) {
                usb_kill_urb(dev->fw_data->fw_urb);
                usb_free_urb(dev->fw_data->fw_urb);
@@ -2352,7 +2352,7 @@ errorREQFW:
 errorFWDATA2:
        usb_free_urb(dev->fw_data->fw_urb);
 errorFWURB:
-       del_timer(&dev->timer);
+       del_timer_sync(&dev->timer);
 errorEP:
        usb_put_dev(dev->udev);
 errorUDEV:

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