CVE-2025-68231 mm/mempool: fix poisoning order>0 pages with HIGHMEM
A kernel bug causes a page fault and system crash when poisoning high-order pages with HIGHMEM enabled, leading to denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Not stated
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-68231?
CVE-2025-68231 is a memory corruption vulnerability in Linux, published on 16 Dec 2025.
Official description
In the Linux kernel, the following vulnerability has been resolved:
mm/mempool: fix poisoning order>0 pages with HIGHMEM
The kernel test has reported:
BUG: unable to handle page fault for address: fffba000 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page *pde = 03171067 *pte = 00000000 Oops: Oops: 0002 [#1] CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Tainted: G T 6.18.0-rc2-00031-gec7f31b2a2d3 #1 NONE a1d066dfe789f54bc7645c7989957d2bdee593ca Tainted: [T]=RANDSTRUCT Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 EIP: memset (arch/x86/include/asm/string_32.h:168 arch/x86/lib/memcpy_32.c:17) Code: a5 8b 4d f4 83 e1 03 74 02 f3 a4 83 c4 04 5e 5f 5d 2e e9 73 41 01 00 90 90 90 3e 8d 74 26 00 55 89 e5 57 56 89 c6 89 d0 89 f7 <f3> aa 89 f0 5e 5f 5d 2e e9 53 41 01 00 cc cc cc 55 89 e5 53 57 56 EAX: 0000006b EBX: 00000015 ECX: 001fefff EDX: 0000006b ESI: fffb9000 EDI: fffba000 EBP: c611fbf0 ESP: c611fbe8 DS: 007b ES: 007b FS: 0000 GS: 0000 SS: 0068 EFLAGS: 00010287 CR0: 80050033 CR2: fffba000 CR3: 0316e000 CR4: 00040690 Call Trace: poison_element (mm/mempool.c:83 mm/mempool.c:102) mempool_init_node (mm/mempool.c:142 mm/mempool.c:226) mempool_init_noprof (mm/mempool.c:250 (discriminator 1)) ? mempool_alloc_pages (mm/mempool.c:640) bio_integrity_initfn (block/bio-integrity.c:483 (discriminator 8)) ? mempool_alloc_pages (mm/mempool.c:640) do_one_initcall (init/main.c:1283)
Christoph found out this is due to the poisoning code not dealing properly with CONFIG_HIGHMEM because only the first page is mapped but then the whole potentially high-order page is accessed.
We could give up on HIGHMEM here, but it's straightforward to fix this with a loop that's mapping, poisoning or checking and unmapping individual pages.
Which versions are affected by CVE-2025-68231?
How do I fix CVE-2025-68231?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2025-68231 being exploited?
There is no known exploitation of CVE-2025-68231 in the wild and no public exploit code.
Sources
Also known as AZL-72458, BELL-CVE-2025-68231, DEBIAN-CVE-2025-68231, GHSA-rgc8-7q99-mqx9, ROOT-OS-DEBIAN-11-CVE-2025-68231, ROOT-OS-DEBIAN-12-CVE-2025-68231 and 4 more.