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media: rc: Fix use-after-free bugs caused by ene_tx_irqsim()

Ricardo Robaina requested to merge rrobaina/centos-stream-9:bz2174411 into main

Bugzilla: https://bugzilla.redhat.com/2174411

CVE: CVE-2023-1118

When the ene device is detaching, function ene_remove() will
be called. But there is no function to cancel tx_sim_timer
in ene_remove(), the timer handler ene_tx_irqsim() could race
with ene_remove(). As a result, the UAF bugs could happen,
the process is shown below.

(cleanup routine)          |        (timer routine)  
                           | mod_timer(&dev->tx_sim_timer, ..)

ene_remove() | (wait a time)
| ene_tx_irqsim()
| dev->hw_lock //USE
| ene_tx_sample(dev) //USE

Fix by adding del_timer_sync(&dev->tx_sim_timer) in ene_remove(),
The tx_sim_timer could stop before ene device is deallocated.

What's more, The rc_unregister_device() and del_timer_sync()
should be called first in ene_remove() and the deallocated
functions such as free_irq(), release_region() and so on
should be called behind them. Because the rc_unregister_device()
is well synchronized. Otherwise, race conditions may happen. The
situations that may lead to race conditions are shown below.

Firstly, the rx receiver is disabled with ene_rx_disable()
before rc_unregister_device() in ene_remove(), which means it
can be enabled again if a process opens /dev/lirc0 between
ene_rx_disable() and rc_unregister_device().

Secondly, the irqaction descriptor is freed by free_irq()
before the rc device is unregistered, which means irqaction
descriptor may be accessed again after it is deallocated.

Thirdly, the timer can call ene_tx_sample() that can write
to the io ports, which means the io ports could be accessed
again after they are deallocated by release_region().

Therefore, the rc_unregister_device() and del_timer_sync()
should be called first in ene_remove().

Suggested by: Sean Young sean@mess.org

Fixes: 9ea53b74 ("V4L/DVB: STAGING: remove lirc_ene0100 driver")
Signed-off-by: Duoming Zhou duoming@zju.edu.cn
Signed-off-by: Sean Young sean@mess.org
Signed-off-by: Mauro Carvalho Chehab mchehab@kernel.org
(cherry picked from commit 29b0589a865b6f66d141d79b2dd1373e4e50fe17)
Signed-off-by: Ricardo Robaina rrobaina@redhat.com

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