CVE-2024-56712

What the bug is

In export_udmabuf(), if dma_buf_fd() fails because the FD table is full, a dma_buf owning the udmabuf has already been created; but the error handling in udmabuf_create() will tear down the udmabuf without doing anything about the containing dma_buf. This leaves a dma_buf in memory that contains a dangling pointer; though that doesn't seem to lead to anything bad except a memory leak. Fix it by moving the dma_buf_fd() call out of export_udmabuf() so that we can give it different error handling. Note that the shape of this code changed a lot in commit 5e72b2b41a21 ("udmabuf: convert udmabuf driver to use folios"); but the memory leak seems to have existed since the introduction of udmabuf.

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

2024-12-29 (22 months ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.19%, higher than 7.8% 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	6.12.7	c9fc8428d425
4.20	6.13	f49856f525ac