CVE-2024-56544 udmabuf: change folios array from kmalloc to kvmalloc
A local attacker can trigger a kernel warning and potential null dereference by creating large udmabuf instances, causing a denial of service.
- 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-2024-56544?
CVE-2024-56544 is a medium-severity vulnerability in Linux kernel, published on 27 Dec 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:
udmabuf: change folios array from kmalloc to kvmalloc
When PAGE_SIZE 4096, MAX_PAGE_ORDER 10, 64bit machine, page_alloc only support 4MB. If above this, trigger this warn and return NULL.
udmabuf can change size limit, if change it to 3072(3GB), and then alloc 3GB udmabuf, will fail create.
[ 4080.876581] ------------[ cut here ]------------ [ 4080.876843] WARNING: CPU: 3 PID: 2015 at mm/page_alloc.c:4556 __alloc_pages+0x2c8/0x350 [ 4080.878839] RIP: 0010:__alloc_pages+0x2c8/0x350 [ 4080.879470] Call Trace: [ 4080.879473] <TASK> [ 4080.879473] ? __alloc_pages+0x2c8/0x350 [ 4080.879475] ? __warn.cold+0x8e/0xe8 [ 4080.880647] ? __alloc_pages+0x2c8/0x350 [ 4080.880909] ? report_bug+0xff/0x140 [ 4080.881175] ? handle_bug+0x3c/0x80 [ 4080.881556] ? exc_invalid_op+0x17/0x70 [ 4080.881559] ? asm_exc_invalid_op+0x1a/0x20 [ 4080.882077] ? udmabuf_create+0x131/0x400
Because MAX_PAGE_ORDER, kmalloc can max alloc 4096 * (1 << 10), 4MB memory, each array entry is pointer(8byte), so can save 524288 pages(2GB).
Further more, costly order(order 3) may not be guaranteed that it can be applied for, due to fragmentation.
This patch change udmabuf array use kvmalloc_array, this can fallback alloc into vmalloc, which can guarantee allocation for any size and does not affect the performance of kmalloc allocations.
Weakness: CWE-476
Which versions are affected by CVE-2024-56544?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-56544?
Apply the vendor's patch.
Is CVE-2024-56544 being exploited?
There is no known exploitation of CVE-2024-56544 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-56237, AZL-56250, BELL-CVE-2024-56544, DEBIAN-CVE-2024-56544, GHSA-xrf5-hv85-5f65, ROOT-OS-DEBIAN-11-CVE-2024-56544 and 4 more.