CVE-2024-38600 ALSA: Fix deadlocks with kctl removals at disconnection
A race condition in the Linux kernel ALSA subsystem can cause a deadlock during device disconnection, leading to a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2024-38600?
CVE-2024-38600 is a medium-severity vulnerability in Linux kernel, published on 19 Jun 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
ALSA: Fix deadlocks with kctl removals at disconnection
In snd_card_disconnect(), we set card->shutdown flag at the beginning, call callbacks and do sync for card->power_ref_sleep waiters at the end. The callback may delete a kctl element, and this can lead to a deadlock when the device was in the suspended state. Namely:
* A process waits for the power up at snd_power_ref_and_wait() in snd_ctl_info() or read/write() inside card->controls_rwsem.
* The system gets disconnected meanwhile, and the driver tries to delete a kctl via snd_ctl_remove*(); it tries to take card->controls_rwsem again, but this is already locked by the above. Since the sleeper isn't woken up, this deadlocks.
An easy fix is to wake up sleepers before processing the driver disconnect callbacks but right after setting the card->shutdown flag. Then all sleepers will abort immediately, and the code flows again.
So, basically this patch moves the wait_event() call at the right timing. While we're at it, just to be sure, call wait_event_all() instead of wait_event(), although we don't use exclusive events on this queue for now.
Weakness: CWE-667
Which versions are affected by CVE-2024-38600?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-38600?
Apply the vendor's patch.
Is CVE-2024-38600 being exploited?
There is no known exploitation of CVE-2024-38600 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2024-38600, DEBIAN-CVE-2024-38600, GHSA-3h59-8483-h44f, UBUNTU-CVE-2024-38600.