CVE-2021-47461 userfaultfd: fix a race between writeprotect and exit_mmap()
A race condition in the Linux kernel userfaultfd subsystem can lead to a system crash or denial of service when a process exits concurrently with writeprotect operations.
- 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-2021-47461?
CVE-2021-47461 is a high-severity vulnerability in Linux kernel, published on 22 May 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:
userfaultfd: fix a race between writeprotect and exit_mmap()
A race is possible when a process exits, its VMAs are removed by exit_mmap() and at the same time userfaultfd_writeprotect() is called.
The race was detected by KASAN on a development kernel, but it appears to be possible on vanilla kernels as well.
Use mmget_not_zero() to prevent the race as done in other userfaultfd operations.
Weakness: CWE-362
Which versions are affected by CVE-2021-47461?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2021-47461?
Apply the vendor's patch.
Is CVE-2021-47461 being exploited?
There is no known exploitation of CVE-2021-47461 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2021-47461, GHSA-q3gr-2743-cwm5, UBUNTU-CVE-2021-47461.