CVE-2024-56544

What the bug is

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.

Where it lives

The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.

drivers/dma-buf/udmabuf.c

What this is

USERSPACE DMA BUFFER DRIVERMAINTAINERS section matched on drivers/dma-buf/udmabuf.c · dri-devel@lists.freedesktop.org · Maintained

Check it on the machine

grep -wE 'CONFIG_DMA_SHARED_BUFFER|CONFIG_UDMABUF' /boot/config-$(uname -r)

Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.

Show whether Debian builds this, per release

Debian does not build this code in 1 release. It does build it in 3 releases, so the answer depends on which release the machine runs.

• bookwormn
• trixieYnot built on armel/rpi, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
• forky, sidYnot built on armhf/armmp, armhf/armmp-lpae, loong64/loong64, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x

n

not enabled on any flavour - this release does not build the code

Y

built in where it is built at all; some flavours do not build it

Build switches

CONFIG_DMA_SHARED_BUFFER, CONFIG_UDMABUF

Reads as

all on means the file is compiled; any one off means it is not.

From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages

Signals

Published

2024-12-27 (22 months ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.22%, higher than 11.4% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

not yet assignedsource

Subsystem

drivers/dma-buf

Upstream fixes

The versions the CNA records as introducing and fixing this, and the commit for each. source

Introduced	Fixed in	Commit
4.20	6.11.11	2acc6192aa85
4.20	6.12.2	85bb72397cb6
4.20	6.13	1c0844c6184e