CVE-2026-80873: KVM: arm64: nv: Write ESR_EL2 for injected nested SError exceptions

CVE-2026-80873: KVM: arm64: nv: Write ESR_EL2 for injected nested SError exceptions

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

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

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

KVM: arm64: nv: Write ESR_EL2 for injected nested SError exceptions

kvm_inject_el2_exception() writes ESR_EL2 for synchronous exceptions
but not for SError. enter_exception64() does not write ESR_ELx for any
exception type, so the constructed syndrome is dropped. A guest L2
hypervisor taking a nested SError observes stale ESR_EL2.

This affects both kvm_inject_nested_serror() and the EASE path in
kvm_inject_nested_sea().

Write ESR_EL2 for except_type_serror, matching except_type_sync.

The Linux kernel CVE team has assigned CVE-2026-80873 to this issue.


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

	Issue introduced in 6.17 with commit 77ee70a073575977b403e9add25f185d614217d8 and fixed in 6.18.40 with commit 09f35145f3a4aacea4d9b914ad895bf5af8fc4ae
	Issue introduced in 6.17 with commit 77ee70a073575977b403e9add25f185d614217d8 and fixed in 7.1.5 with commit 29227821e2320ff6a174c91742b4ce221fe8d563
	Issue introduced in 6.17 with commit 77ee70a073575977b403e9add25f185d614217d8 and fixed in 7.2 with commit e2cb1f4578625e71f461d5c1ce70984193389cbb

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-2026-80873
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/emulate-nested.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/09f35145f3a4aacea4d9b914ad895bf5af8fc4ae
	https://git.kernel.org/stable/c/29227821e2320ff6a174c91742b4ce221fe8d563
	https://git.kernel.org/stable/c/e2cb1f4578625e71f461d5c1ce70984193389cbb