media: netup_unidvb: fix use-after-free at del_timer()

stable inclusion
from stable-v5.10.181
commit f9982db735a8495eee14267cf193c806b957e942
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8GJZJ

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f9982db735a8495eee14267cf193c806b957e942

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

[ Upstream commit 0f5bb36b ]

When Universal DVB card is detaching, netup_unidvb_dma_fini()
uses del_timer() to stop dma->timeout timer. But when timer
handler netup_unidvb_dma_timeout() is running, del_timer()
could not stop it. As a result, the use-after-free bug could
happen. The process is shown below:

    (cleanup routine)          |        (timer routine)
                               | mod_timer(&dev->tx_sim_timer, ..)
netup_unidvb_finidev()         | (wait a time)
  netup_unidvb_dma_fini()      | netup_unidvb_dma_timeout()
    del_timer(&dma->timeout);  |
                               |   ndev->pci_dev->dev //USE

Fix by changing del_timer() to del_timer_sync().

Link: https://lore.kernel.org/linux-media/20230308125514.4208-1-duoming@zju.edu.cn


Fixes: 52b1eaf4 ("[media] netup_unidvb: NetUP Universal DVB-S/S2/T/T2/C PCI-E card driver")
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>
(cherry picked from commit 74385954)