CVE Published: 19/06/2024 |
CVE Updated: 05/11/2024 |
CVE Year: 2024 Source: Linux |
Vendor: Linux |
Product: Linux Status : PUBLISHED
CVE-2024-38610 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.