linux-cve-announce - CVE-2025-37885: KVM: x86: Reset IRTE to host control if *new* route isn't postable

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Message-ID: <2025050945-CVE-2025-37885-a5d9@gregkh>
Date: Fri,  9 May 2025 08:45:52 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-37885: KVM: x86: Reset IRTE to host control if *new* route isn't postable

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

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

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

KVM: x86: Reset IRTE to host control if *new* route isn't postable

Restore an IRTE back to host control (remapped or posted MSI mode) if the
*new* GSI route prevents posting the IRQ directly to a vCPU, regardless of
the GSI routing type.  Updating the IRTE if and only if the new GSI is an
MSI results in KVM leaving an IRTE posting to a vCPU.

The dangling IRTE can result in interrupts being incorrectly delivered to
the guest, and in the worst case scenario can result in use-after-free,
e.g. if the VM is torn down, but the underlying host IRQ isn't freed.

The Linux kernel CVE team has assigned CVE-2025-37885 to this issue.


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

	Issue introduced in 4.4 with commit efc644048ecde54f016011fe10110addd0de348f and fixed in 5.10.237 with commit e5f2dee9f7fcd2ff4b97869f3c66a0d89c167769
	Issue introduced in 4.4 with commit efc644048ecde54f016011fe10110addd0de348f and fixed in 5.15.181 with commit 116c7d35b8f72eac383b9fd371d7c1a8ffc2968b
	Issue introduced in 4.4 with commit efc644048ecde54f016011fe10110addd0de348f and fixed in 6.1.136 with commit 023816bd5fa46fab94d1e7917fe131b79ed1fb41
	Issue introduced in 4.4 with commit efc644048ecde54f016011fe10110addd0de348f and fixed in 6.6.89 with commit 3481fd96d801715942b6f69fe251133128156f30
	Issue introduced in 4.4 with commit efc644048ecde54f016011fe10110addd0de348f and fixed in 6.12.26 with commit b5de7ac74f69603ad803c524b840bffd36368fc3
	Issue introduced in 4.4 with commit efc644048ecde54f016011fe10110addd0de348f and fixed in 6.14.5 with commit 3066ec21d1a33896125747f68638725f456308db
	Issue introduced in 4.4 with commit efc644048ecde54f016011fe10110addd0de348f and fixed in 6.15-rc4 with commit 9bcac97dc42d2f4da8229d18feb0fe2b1ce523a2

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-2025-37885
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/x86/kvm/svm/avic.c
	arch/x86/kvm/vmx/posted_intr.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/e5f2dee9f7fcd2ff4b97869f3c66a0d89c167769
	https://git.kernel.org/stable/c/116c7d35b8f72eac383b9fd371d7c1a8ffc2968b
	https://git.kernel.org/stable/c/023816bd5fa46fab94d1e7917fe131b79ed1fb41
	https://git.kernel.org/stable/c/3481fd96d801715942b6f69fe251133128156f30
	https://git.kernel.org/stable/c/b5de7ac74f69603ad803c524b840bffd36368fc3
	https://git.kernel.org/stable/c/3066ec21d1a33896125747f68638725f456308db
	https://git.kernel.org/stable/c/9bcac97dc42d2f4da8229d18feb0fe2b1ce523a2