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Date: Thu, 2 Mar 2023 08:56:46 +0800 (GMT+08:00)
From: duoming@....edu.cn
To: oss-security@...ts.openwall.com
Subject: Linux kernel: CVE-2023-1118: UAF vulnerabilities in
"drivers/media/rc" directory
Hello there,
There are use-after-free vulnerabilities in drivers/media/rc/ene_ir.c of linux that
allow attacker to crash linux kernel without any privilege by detaching rc device.
=*=*=*=*=*=*=*=*= Bug Details =*=*=*=*=*=*=*=*=
When the rc device is detaching, function ene_remove() will be called.
But the synchronizations in ene_remove() are bad. 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().
(cleanup routine) | (open routine)
ene_remove() |
ene_rx_disable(dev); | ene_open()
| ene_rx_enable(dev); //re-enable!
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.
(free routine) | (use routine)
ene_remove() | ene_rx_enable()
free_irq(dev->irq, ...); //FREE | ene_rx_enable_hw()
| ene_write_reg(..., dev->irq << 1) //USE
|
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().
(free routine) | (use routine)
ene_remove() | ene_tx_sample()
release_region(dev->hw_io, ...); //FREE | ene_write_reg()
| outb(..., dev->hw_io + ENE_IO) //USE
Fourthly, 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.
(free routine) | (use routine)
| mod_timer(&dev->tx_sim_timer, ..)
ene_remove() | (wait a time)
kfree(dev) //FREE | ene_tx_irqsim()
| dev->hw_lock //USE
| ene_tx_sample(dev) //USE
=*=*=*=*=*=*=*=*= Bug Effects =*=*=*=*=*=*=*=*=
The vulnerabilities could crash the kernel and cause denial-of-service by detaching rc device.
=*=*=*=*=*=*=*=*= Bug Fix =*=*=*=*=*=*=*=*=*=*=
The patch that have been applied to mainline Linux kernel is shown below.
https://github.com/torvalds/linux/commit/29b0589a865b6f66d141d79b2dd1373e4e50fe17
=*=*=*=*=*=*=*=*= Timeline =*=*=*=*=*=*=*=*=*=
2023-02-08: commit 29b0589a865b was accepted to mainline kernel
2023-03-01: CVE-2023-1118 was assigned by redhat.
=*=*=*=*=*=*=*=*= Credit =*=*=*=*=*=*=*=*=
Duoming Zhou <duoming@....edu.cn>
Best Regards,
Duoming Zhou
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