CVE-2024-47674 Information

Description

In the Linux kernel the following vulnerability has been resolved:

mm: avoid leaving partial pfn mappings around in error case

As Jann points out PFN mappings are special because unlike normal memory mappings there is no lifetime information associated with the mapping - it is just a raw mapping of PFNs with no reference counting of a ‘struct page’.

That’s all very much intentional but it does mean that it’s easy to mess up the cleanup in case of errors. Yes a failed mmap() will always eventually clean up any partial mappings but without any explicit lifetime in the page table mapping itself it’s very easy to do the error handling in the wrong order.

In particular it’s easy to mistakenly free the physical backing store before the page tables are actually cleaned up and (temporarily) have stale dangling PTE entries.

To make this situation less error-prone just make sure that any partial pfn mapping is torn down early before any other error handling.

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Reference

https://git.kernel.org/stable/c/65d0db500d7c07f0f76fc24a4d837791c4862cd2 https://git.kernel.org/stable/c/a95a24fcaee1b892e47d5e6dcc403f713874ee80 https://git.kernel.org/stable/c/954fd4c81f22c4b6ba65379a81fd252971bf4ef3 https://git.kernel.org/stable/c/79a61cc3fc0466ad2b7b89618a6157785f0293b3 https://git.kernel.org/stable/c/5b2c8b34f6d76bfbd1dd4936eb8a0fbfb9af3959 https://project-zero.issues.chromium.org/issues/366053091

Attack Complexity

LOW

Privileges Required

LOW

User Interaction Required

LOW

Scope

NONE

Confidentiality Impact

UNCHANGED

Integrity Impact

NONE

Availability Impact

NONE

Base Score

HIGH

Base Severity

5.5