CVE-2024-38610 drivers/virt/acrn: fix PFNMAP PTE checks in acrn_vm_ram_map()
A use-after-free vulnerability in the Linux kernel ACRN driver allows attackers to execute arbitrary code or escalate privileges via improper PTE checks.
- 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-2024-38610?
CVE-2024-38610 is a high-severity use after free vulnerability in Linux kernel, published on 19 Jun 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:
drivers/virt/acrn: fix PFNMAP PTE checks in acrn_vm_ram_map()
Patch series "mm: follow_pte() improvements and acrn follow_pte() fixes".
Patch #1 fixes a bunch of issues I spotted in the acrn driver. It compiles, that's all I know. I'll appreciate some review and testing from acrn folks.
Patch #2+#3 improve follow_pte(), passing a VMA instead of the MM, adding more sanity checks, and improving the documentation. Gave it a quick test on x86-64 using VM_PAT that ends up using follow_pte().
This patch (of 3):
We currently miss handling various cases, resulting in a dangerous follow_pte() (previously follow_pfn()) usage.
(1) We're not checking PTE write permissions.
Maybe we should simply always require pte_write() like we do for pin_user_pages_fast(FOLL_WRITE)? Hard to tell, so let's check for ACRN_MEM_ACCESS_WRITE for now.
(2) We're not rejecting refcounted pages.
As we are not using MMU notifiers, messing with refcounted pages is dangerous and can result in use-after-free. Let's make sure to reject them.
(3) We are only looking at the first PTE of a bigger range.
We only lookup a single PTE, but memmap->len may span a larger area. Let's loop over all involved PTEs and make sure the PFN range is actually contiguous. Reject everything else: it couldn't have worked either way, and rather made use access PFNs we shouldn't be accessing.
Weakness: CWE-416
Which versions are affected by CVE-2024-38610?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-38610?
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-2024-38610 being exploited?
There is no known exploitation of CVE-2024-38610 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2024-38610, DEBIAN-CVE-2024-38610, GHSA-h3h3-jq7c-xgpc, UBUNTU-CVE-2024-38610.