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

[ Upstream commit 34e7434ba4e97f4b85c1423a59b2922ba7dff2ea ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/atm/nicstar.c b/drivers/atm/nicstar.c
index 49da83f87170b8a2fa803b2d436864677d7af894..486d7a11403110f010c0c29646ae4fb6b5dea360 100644 (file)
--- a/drivers/atm/nicstar.c
+++ b/drivers/atm/nicstar.c
@@ -298,7 +298,7 @@ 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);