Saint Dirty Pipe, Who Wrote in Read-Only Files

Patron of Linux pipes, files you thought were protected, and page-cache pages reused too casually.

Life

On 7 March 2022 Max Kellermann published CVE-2022-0847, named Dirty Pipe as a nod to Dirty COW. An uninitialised field in the Linux kernel's pipes let an unprivileged user write into read-only files through the page cache: from there to overwriting system files and becoming root was a short step. The flaw had entered the kernel in 2020.

Prayer

O Saint Dirty Pipe, who fills with writing the files that kept silent, teach the kernel to initialise every field before using it. Amen.

How to celebrate

Celebrated by updating the Linux kernel to 5.16.11, 5.15.25 or 5.10.102 and remembering that "read-only" holds only as long as the kernel cooperates.

Dirty pipe, talkative file.