CVE-2024-50191 ext4: don't set SB_RDONLY after filesystem errors
A flaw in the Linux kernel ext4 filesystem can cause warnings and potential instability when handling filesystem errors, leading to 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-2024-50191?
CVE-2024-50191 is a medium-severity denial of service vulnerability in Linux kernel, published on 8 Nov 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:
ext4: don't set SB_RDONLY after filesystem errors
When the filesystem is mounted with errors=remount-ro, we were setting SB_RDONLY flag to stop all filesystem modifications. We knew this misses proper locking (sb->s_umount) and does not go through proper filesystem remount procedure but it has been the way this worked since early ext2 days and it was good enough for catastrophic situation damage mitigation. Recently, syzbot has found a way (see link) to trigger warnings in filesystem freezing because the code got confused by SB_RDONLY changing under its hands. Since these days we set EXT4_FLAGS_SHUTDOWN on the superblock which is enough to stop all filesystem modifications, modifying SB_RDONLY shouldn't be needed. So stop doing that.
Which versions are affected by CVE-2024-50191?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-50191?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2024-50191 being exploited?
There is no known exploitation of CVE-2024-50191 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2024-50191, DEBIAN-CVE-2024-50191, GHSA-639p-pgpg-5qr5, ROOT-OS-DEBIAN-11-CVE-2024-50191, UBUNTU-CVE-2024-50191.