linux-cve-announce - CVE-2024-35843: iommu/vt-d: Use device rbtree in iopf reporting path

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Message-ID: <2024051717-CVE-2024-35843-516e@gregkh>
Date: Fri, 17 May 2024 16:40:18 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-35843: iommu/vt-d: Use device rbtree in iopf reporting path

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

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

iommu/vt-d: Use device rbtree in iopf reporting path

The existing I/O page fault handler currently locates the PCI device by
calling pci_get_domain_bus_and_slot(). This function searches the list
of all PCI devices until the desired device is found. To improve lookup
efficiency, replace it with device_rbtree_find() to search the device
within the probed device rbtree.

The I/O page fault is initiated by the device, which does not have any
synchronization mechanism with the software to ensure that the device
stays in the probed device tree. Theoretically, a device could be released
by the IOMMU subsystem after device_rbtree_find() and before
iopf_get_dev_fault_param(), which would cause a use-after-free problem.

Add a mutex to synchronize the I/O page fault reporting path and the IOMMU
release device path. This lock doesn't introduce any performance overhead,
as the conflict between I/O page fault reporting and device releasing is
very rare.

The Linux kernel CVE team has assigned CVE-2024-35843 to this issue.

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

	Fixed in 6.8.2 with commit 3d39238991e7
	Fixed in 6.9 with commit def054b01a86

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-2024-35843
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/iommu/intel/dmar.c
	drivers/iommu/intel/iommu.c
	drivers/iommu/intel/iommu.h
	drivers/iommu/intel/svm.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/3d39238991e745c5df85785604f037f35d9d1b15
	https://git.kernel.org/stable/c/def054b01a867822254e1dda13d587f5c7a99e2a