CVE-2024-38610
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".
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.21%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.1
- 7.8 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 0.21% probability · 12th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-416
- Affected
- linux/linux kernel
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
References
- https://git.kernel.org/stable/c/2c8d6e24930b8ef7d4a81787627c559ae0e0d3bbPatch
- https://git.kernel.org/stable/c/3d6586008f7b638f91f3332602592caa8b00b559Patch
- https://git.kernel.org/stable/c/4c4ba3cf3a15ccfbaf787d0296fa42cdb00da9b4Patch
- https://git.kernel.org/stable/c/5c6705aa47b5b78d7ad36fea832bb69caa5bf49aPatch
- https://git.kernel.org/stable/c/afeb0e69627695f759fc73c39c1640dbf8649b32Patch
- https://git.kernel.org/stable/c/e873f36ec890bece26ecce850e969917bceebbb6Patch
- https://git.kernel.org/stable/c/2c8d6e24930b8ef7d4a81787627c559ae0e0d3bbPatch
- https://git.kernel.org/stable/c/3d6586008f7b638f91f3332602592caa8b00b559Patch
- https://git.kernel.org/stable/c/4c4ba3cf3a15ccfbaf787d0296fa42cdb00da9b4Patch
- https://git.kernel.org/stable/c/5c6705aa47b5b78d7ad36fea832bb69caa5bf49aPatch
- https://git.kernel.org/stable/c/afeb0e69627695f759fc73c39c1640dbf8649b32Patch
- https://git.kernel.org/stable/c/e873f36ec890bece26ecce850e969917bceebbb6Patch
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.