atm: nicstar: Fix possible use-after-free in nicstar_cleanup()

This module's remove path calls del_timer(). However, that function
does not wait until the timer handler finishes. This means that the
timer handler may still be running after the driver's remove function
has finished, which would result in a use-after-free.

Fix by calling del_timer_sync(), which makes sure the timer handler
has finished, and unable to re-schedule itself.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zou Wei <zou_wei@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/atm/nicstar.c b/drivers/atm/nicstar.c
index 5c7e4df159b9128d6bda914c1e6365f3fe6e6bb1..b015c3e143361eceea6414287472bc549f9f457e 100644 (file)
--- a/drivers/atm/nicstar.c
+++ b/drivers/atm/nicstar.c
@@ -299,7 +299,7 @@ static void __exit nicstar_cleanup(void)
 {
        XPRINTK("nicstar: nicstar_cleanup() called.\n");
 
-       del_timer(&ns_timer);
+       del_timer_sync(&ns_timer);
 
        pci_unregister_driver(&nicstar_driver);