CVE-2022-50277 ext4: don't allow journal inode to have encrypt flag
A local attacker can cause a kernel crash by mounting a crafted ext4 filesystem with the inlinecrypt option, 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-2022-50277?
CVE-2022-50277 is a medium-severity vulnerability in Linux kernel, published on 15 Sep 2025. 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 allow journal inode to have encrypt flag
Mounting a filesystem whose journal inode has the encrypt flag causes a NULL dereference in fscrypt_limit_io_blocks() when the 'inlinecrypt' mount option is used.
The problem is that when jbd2_journal_init_inode() calls bmap(), it eventually finds its way into ext4_iomap_begin(), which calls fscrypt_limit_io_blocks(). fscrypt_limit_io_blocks() requires that if the inode is encrypted, then its encryption key must already be set up. That's not the case here, since the journal inode is never "opened" like a normal file would be. Hence the crash.
A reproducer is:
mkfs.ext4 -F /dev/vdb debugfs -w /dev/vdb -R "set_inode_field <8> flags 0x80808" mount /dev/vdb /mnt -o inlinecrypt
To fix this, make ext4 consider journal inodes with the encrypt flag to be invalid. (Note, maybe other flags should be rejected on the journal inode too. For now, this is just the minimal fix for the above issue.)
I've marked this as fixing the commit that introduced the call to fscrypt_limit_io_blocks(), since that's what made an actual crash start being possible. But this fix could be applied to any version of ext4 that supports the encrypt feature.
Weakness: CWE-476
Which versions are affected by CVE-2022-50277?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2022-50277?
Apply the vendor's patch.
Is CVE-2022-50277 being exploited?
There is no known exploitation of CVE-2022-50277 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2022-50277, GHSA-5935-5rv9-4v2p, UBUNTU-CVE-2022-50277.