CVE-2023-53429

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

btrfs: don't check PageError in __extent_writepage

__extent_writepage currenly sets PageError whenever any error happens,

and the also checks for PageError to decide if to call error handling.

This leads to very unclear responsibility for cleaning up on errors.

In the VM and generic writeback helpers the basic idea is that once

I/O is fired off all error handling responsibility is delegated to the

end I/O handler. But if that end I/O handler sets the PageError bit,

and the submitter checks it, the bit could in some cases leak into the

submission context for fast enough I/O.

Fix this by simply not checking PageError and just using the local

ret variable to check for submission errors. This also fundamentally

solves the long problem documented in a comment in __extent_writepage

by never leaking the error bit into the submission context.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References