This is a note to let you know that I've just added the patch titled
media: rc: Fix use-after-free bugs caused by ene_tx_irqsim()
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
media-rc-fix-use-after-free-bugs-caused-by-ene_tx_ir.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit cf44d2c21cc08920e1afef36e7777e0a57696d92
Author: Duoming Zhou <duoming@xxxxxxxxxx>
Date: Tue Jan 24 08:55:33 2023 +0100
media: rc: Fix use-after-free bugs caused by ene_tx_irqsim()
[ Upstream commit 29b0589a865b6f66d141d79b2dd1373e4e50fe17 ]
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@xxxxxxxx>
Fixes: 9ea53b74df9c ("V4L/DVB: STAGING: remove lirc_ene0100 driver")
Signed-off-by: Duoming Zhou <duoming@xxxxxxxxxx>
Signed-off-by: Sean Young <sean@xxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/media/rc/ene_ir.c b/drivers/media/rc/ene_ir.c
index 82867a2a60b0e..20cadff242cf9 100644
--- a/drivers/media/rc/ene_ir.c
+++ b/drivers/media/rc/ene_ir.c
@@ -1106,6 +1106,8 @@ static void ene_remove(struct pnp_dev *pnp_dev)
struct ene_device *dev = pnp_get_drvdata(pnp_dev);
unsigned long flags;
+ rc_unregister_device(dev->rdev);
+ del_timer_sync(&dev->tx_sim_timer);
spin_lock_irqsave(&dev->hw_lock, flags);
ene_rx_disable(dev);
ene_rx_restore_hw_buffer(dev);
@@ -1113,7 +1115,6 @@ static void ene_remove(struct pnp_dev *pnp_dev)
free_irq(dev->irq, dev);
release_region(dev->hw_io, ENE_IO_SIZE);
- rc_unregister_device(dev->rdev);
kfree(dev);
}
