CVE-2026-64286: KVM: arm64: Clear __hyp_running_vcpu when flushing the pKVM hyp vCPU

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

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

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

KVM: arm64: Clear __hyp_running_vcpu when flushing the pKVM hyp vCPU

flush_hyp_vcpu() copies the host vCPU context into the hyp's private
vCPU on every run. ctxt_to_vcpu() expects a guest context to have a
NULL __hyp_running_vcpu, which is only ever set on the host context, so
that it resolves the vCPU via container_of(). While this is generally
the case, flush_hyp_vcpu() copies the context verbatim and does not
enforce this, so a value provided by the host is dereferenced at EL2
(host -> EL2).

Fix by clearing __hyp_running_vcpu after the copy.

The Linux kernel CVE team has assigned CVE-2026-64286 to this issue.


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

	Issue introduced in 6.2 with commit be66e67f175096f283c9d5614c4991fc9e7ed975 and fixed in 6.6.145 with commit 477145860dba4c30f0b4e36f02f4c5291c1c888b
	Issue introduced in 6.2 with commit be66e67f175096f283c9d5614c4991fc9e7ed975 and fixed in 6.12.97 with commit dfaef40d8a1533940fc1af788d70fce07362b4ce
	Issue introduced in 6.2 with commit be66e67f175096f283c9d5614c4991fc9e7ed975 and fixed in 6.18.39 with commit 6bea2f8becdb20d34378493c3b77a9b9cf8c6cfa
	Issue introduced in 6.2 with commit be66e67f175096f283c9d5614c4991fc9e7ed975 and fixed in 7.1.4 with commit d4f4d61715d1061ba83b88196a3605662be30750
	Issue introduced in 6.2 with commit be66e67f175096f283c9d5614c4991fc9e7ed975 and fixed in 7.2-rc1 with commit e8042f6e1d7befb2fb6b10a75918642bcd0acf9a

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-2026-64286
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:
	arch/arm64/kvm/hyp/nvhe/hyp-main.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/477145860dba4c30f0b4e36f02f4c5291c1c888b
	https://git.kernel.org/stable/c/dfaef40d8a1533940fc1af788d70fce07362b4ce
	https://git.kernel.org/stable/c/6bea2f8becdb20d34378493c3b77a9b9cf8c6cfa
	https://git.kernel.org/stable/c/d4f4d61715d1061ba83b88196a3605662be30750
	https://git.kernel.org/stable/c/e8042f6e1d7befb2fb6b10a75918642bcd0acf9a