CVE-2024-26810: vfio/pci: Lock external INTx masking ops

CVE-2024-26810: vfio/pci: Lock external INTx masking ops

[Greg Kroah-Hartman]

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

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

vfio/pci: Lock external INTx masking ops

Mask operations through config space changes to DisINTx may race INTx
configuration changes via ioctl.  Create wrappers that add locking for
paths outside of the core interrupt code.

In particular, irq_type is updated holding igate, therefore testing
is_intx() requires holding igate.  For example clearing DisINTx from
config space can otherwise race changes of the interrupt configuration.

This aligns interfaces which may trigger the INTx eventfd into two
camps, one side serialized by igate and the other only enabled while
INTx is configured.  A subsequent patch introduces synchronization for
the latter flows.

The Linux kernel CVE team has assigned CVE-2024-26810 to this issue.


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

	Issue introduced in 3.6 with commit 89e1f7d4c66d and fixed in 6.1.84 with commit 3fe0ac10bd11
	Issue introduced in 3.6 with commit 89e1f7d4c66d and fixed in 6.6.24 with commit 04a4a017b9ff
	Issue introduced in 3.6 with commit 89e1f7d4c66d and fixed in 6.7.12 with commit 6fe478d855b2
	Issue introduced in 3.6 with commit 89e1f7d4c66d and fixed in 6.8.3 with commit 03505e3344b0
	Issue introduced in 3.6 with commit 89e1f7d4c66d and fixed in 6.9-rc1 with commit 810cd4bb5345

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-2024-26810
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:
	drivers/vfio/pci/vfio_pci_intrs.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/3fe0ac10bd117df847c93408a9d428a453cd60e5
	https://git.kernel.org/stable/c/04a4a017b9ffd7b0f427b8c376688d14cb614651
	https://git.kernel.org/stable/c/6fe478d855b20ac1eb5da724afe16af5a2aaaa40
	https://git.kernel.org/stable/c/03505e3344b0576fd619416793a31eae9c5b73bf
	https://git.kernel.org/stable/c/810cd4bb53456d0503cc4e7934e063835152c1b7