linux

iv/linux

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Duoming Zhou 29b0589a86 media: rc: Fix use-after-free bugs caused by ene_tx_irqsim()

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: 9ea53b74df9c ("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>

2023-02-08 07:49:22 +01:00

cec

media: Switch to use dev_err_probe() helper

2022-12-07 17:58:46 +01:00

common

media: videobuf2-core: drop obsolete sanity check in __vb2_queue_free()

2023-02-06 08:58:22 +01:00

dvb-core

Driver Core changes for 6.2-rc1

2022-12-16 03:54:54 -08:00

dvb-frontends

media: dvb-frontends/tc90522: Convert to i2c's .probe_new()