CVE-2026-72278: KVM: arm64: nv: Re-translate VNCR before injecting abort

CVE-2026-72278: KVM: arm64: nv: Re-translate VNCR before injecting abort

[Greg Kroah-Hartman]

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

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

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

KVM: arm64: nv: Re-translate VNCR before injecting abort

KVM faults in the VNCR page with FOLL_WRITE whenever the guest aborts
for a write, similar to how a regular stage-2 mapping is handled. It is
entirely possible that the guest reads from the VNCR before writing to
it, in which case the PFN could only be read-only.

Invalidate the VNCR TLB and re-fetch the translation upon taking a VNCR
abort, allowing the host mapping to be faulted in for write the second
time around. Interestingly enough, this also satisfies the ordering
requirements of FEAT_ETS2/3 between descriptor updates and MMU faults.

The Linux kernel CVE team has assigned CVE-2026-72278 to this issue.


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

	Issue introduced in 6.16 with commit 2a359e072596fcb2e9e85017a865e3618a2fe5b5 and fixed in 6.18.40 with commit ea7a76d7d614b5f82b4d0785f9af3550e860a71a
	Issue introduced in 6.16 with commit 2a359e072596fcb2e9e85017a865e3618a2fe5b5 and fixed in 7.1.5 with commit 0a5dd8cf4d58ea28da132c2097cd1c525302ac48
	Issue introduced in 6.16 with commit 2a359e072596fcb2e9e85017a865e3618a2fe5b5 and fixed in 7.2-rc4 with commit bb645aa0a4caeaf7f9cd32e9a948594d434c1a8f

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-2026-72278
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/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/ea7a76d7d614b5f82b4d0785f9af3550e860a71a
	https://git.kernel.org/stable/c/0a5dd8cf4d58ea28da132c2097cd1c525302ac48
	https://git.kernel.org/stable/c/bb645aa0a4caeaf7f9cd32e9a948594d434c1a8f