CVE-2024-47674 mm: avoid leaving partial pfn mappings around in error case
A use-after-free vulnerability in the Linux kernel's PFN mapping error handling allows attackers to execute arbitrary code or escalate privileges.
- 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-2024-47674?
CVE-2024-47674 is a high-severity use after free vulnerability in Linux kernel, published on 15 Oct 2024. 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:
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.
Weakness: CWE-459
Which versions are affected by CVE-2024-47674?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-47674?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2024-47674 being exploited?
There is no known exploitation of CVE-2024-47674 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-50582, AZL-50597, BELL-CVE-2024-47674, DEBIAN-CVE-2024-47674, GHSA-qjwp-794r-6x7v, UBUNTU-CVE-2024-47674.