CVE-2022-0847

Published: 7 March 2022

A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe and push_pipe functions in the Linux kernel and could thus contain stale values. An unprivileged local user could use this flaw to write to pages in the page cache backed by read only files and as such escalate their privileges on the system.

From the Ubuntu Security Team

Max Kellermann discovered that the Linux kernel incorrectly handled Unix pipes. A local attacker could potentially use this to modify any file that could be opened for reading.

Notes

The specific flaw exists in the bionic and focal, but is not
currently exploitable due to lack of a flag that was introduced
in kernel 5.8. The flaw will be fixed as part of the next round
of bionic and focal kernel updates in case some other way of
exploiting it is discovered in the future.
The hardware enablement kernel for focal, linux-hwe-5.13, was
updated to fix this issue in USN-5317-1.

Status

Severity score breakdown

References

• https://dirtypipe.cm4all.com/
• https://www.openwall.com/lists/oss-security/2022/03/07/1
• https://ubuntu.com/security/notices/USN-5317-1
• https://wiki.ubuntu.com/SecurityTeam/KnowledgeBase/DirtyPipe
• https://ubuntu.com/security/notices/USN-5362-1
• https://www.cve.org/CVERecord?id=CVE-2022-0847
• NVD
• Launchpad
• Debian