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

stable inclusion
from stable-5.10.51
commit a7f7c42e31157d1f0871d6a8e1a0b73a6b4ea785
bugzilla: 175263 https://gitee.com/openeuler/kernel/issues/I4DT6F

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a7f7c42e31157d1f0871d6a8e1a0b73a6b4ea785

--------------------------------

[ Upstream commit 34e7434b ]

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: NHulk Robot <hulkci@huawei.com>
Signed-off-by: NZou Wei <zou_wei@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/atm/nicstar.c

@@ -297,7 +297,7 @@ 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);