CVE-2021-47577 io-wq: check for wq exit after adding new worker task_work
A race condition in the Linux kernel io-wq subsystem can lead to a denial of service by allowing worker creation after exit cancellation.
- 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-2021-47577?
CVE-2021-47577 is a high-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:
io-wq: check for wq exit after adding new worker task_work
We check IO_WQ_BIT_EXIT before attempting to create a new worker, and wq exit cancels pending work if we have any. But it's possible to have a race between the two, where creation checks exit finding it not set, but we're in the process of exiting. The exit side will cancel pending creation task_work, but there's a gap where we add task_work after we've canceled existing creations at exit time.
Fix this by checking the EXIT bit post adding the creation task_work. If it's set, run the same cancelation that exit does.
Weakness: CWE-362
Which versions are affected by CVE-2021-47577?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2021-47577?
Apply the vendor's patch.
Is CVE-2021-47577 being exploited?
There is no known exploitation of CVE-2021-47577 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2021-47577, GHSA-5c74-rw46-pr2c, ROOT-OS-DEBIAN-11-CVE-2021-47577, UBUNTU-CVE-2021-47577.