Subject: CVE-2024-35878: of: module: prevent NULL pointer dereference in vsnprintf()

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

of: module: prevent NULL pointer dereference in vsnprintf()

In of_modalias(), we can get passed the str and len parameters which would
cause a kernel oops in vsnprintf() since it only allows passing a NULL ptr
when the length is also 0. Also, we need to filter out the negative values
of the len parameter as these will result in a really huge buffer since
snprintf() takes size_t parameter while ours is ssize_t...

Found by Linux Verification Center (linuxtesting.org) with the Svace static
analysis tool.

The Linux kernel CVE team has assigned CVE-2024-35878 to this issue.

Affected and fixed versions
===========================

	Fixed in 6.6.26 with commit e4a449368a2c
	Fixed in 6.8.5 with commit 544561dc56f7
	Fixed in 6.9 with commit a1aa5390cc91

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2024-35878
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	drivers/of/module.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/e4a449368a2ce6d57a775d0ead27fc07f5a86e5b
	https://git.kernel.org/stable/c/544561dc56f7e69a053c25e11e6170f48bb97898
	https://git.kernel.org/stable/c/a1aa5390cc912934fee76ce80af5f940452fa987