CVE-2024-35918: randomize_kstack: Improve entropy diffusion

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

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

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

randomize_kstack: Improve entropy diffusion

The kstack_offset variable was really only ever using the low bits for
kernel stack offset entropy. Add a ror32() to increase bit diffusion.

The Linux kernel CVE team has assigned CVE-2024-35918 to this issue.


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

	Issue introduced in 5.13 with commit 39218ff4c625 and fixed in 5.15.155 with commit dfb2ce952143
	Issue introduced in 5.13 with commit 39218ff4c625 and fixed in 6.1.86 with commit e80b4980af26
	Issue introduced in 5.13 with commit 39218ff4c625 and fixed in 6.6.27 with commit 300a2b9c2b28
	Issue introduced in 5.13 with commit 39218ff4c625 and fixed in 6.8.6 with commit 6be74b1e21f8
	Issue introduced in 5.13 with commit 39218ff4c625 and fixed in 6.9 with commit 9c573cd31343

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-2024-35918
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:
	include/linux/randomize_kstack.h


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/dfb2ce952143de60dd756ed666901236c76cb3fa
	https://git.kernel.org/stable/c/e80b4980af2688d8ff69c157ffa773dd1f1eb02c
	https://git.kernel.org/stable/c/300a2b9c2b28282974ee300bb5d5025cbbb1f64c
	https://git.kernel.org/stable/c/6be74b1e21f8de4c48af772c2f658b464bfe6145
	https://git.kernel.org/stable/c/9c573cd313433f6c1f7236fe64b9b743500c1628