linux-cve-announce - CVE-2025-38623: PCI: pnv_php: Fix surprise plug detection and recovery

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Message-ID: <2025082230-CVE-2025-38623-1996@gregkh>
Date: Fri, 22 Aug 2025 18:00:32 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-38623: PCI: pnv_php: Fix surprise plug detection and recovery

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

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

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

PCI: pnv_php: Fix surprise plug detection and recovery

The existing PowerNV hotplug code did not handle surprise plug events
correctly, leading to a complete failure of the hotplug system after device
removal and a required reboot to detect new devices.

This comes down to two issues:

 1) When a device is surprise removed, often the bridge upstream
    port will cause a PE freeze on the PHB.  If this freeze is not
    cleared, the MSI interrupts from the bridge hotplug notification
    logic will not be received by the kernel, stalling all plug events
    on all slots associated with the PE.

 2) When a device is removed from a slot, regardless of surprise or
    programmatic removal, the associated PHB/PE ls left frozen.
    If this freeze is not cleared via a fundamental reset, skiboot
    is unable to clear the freeze and cannot retrain / rescan the
    slot.  This also requires a reboot to clear the freeze and redetect
    the device in the slot.

Issue the appropriate unfreeze and rescan commands on hotplug events,
and don't oops on hotplug if pci_bus_to_OF_node() returns NULL.

[bhelgaas: tidy comments]

The Linux kernel CVE team has assigned CVE-2025-38623 to this issue.


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

	Fixed in 6.1.148 with commit 473999ba937eac9776be791deed7c84a21d7880b
	Fixed in 6.6.102 with commit 6e7b24c71e530a6c1d656e73d8a30ee081656844
	Fixed in 6.12.42 with commit 48c6935a34981bb56f35be0774ec1f30c6e386f8
	Fixed in 6.15.10 with commit 1d2f63680c5719a5da92639e981c6c9a87fcee08
	Fixed in 6.16.1 with commit 78d20b8c13075eae3d884c21db7a09a6bbdda5b2
	Fixed in 6.17-rc1 with commit a2a2a6fc2469524caa713036297c542746d148dc

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-2025-38623
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/powerpc/kernel/pci-hotplug.c
	drivers/pci/hotplug/pnv_php.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/473999ba937eac9776be791deed7c84a21d7880b
	https://git.kernel.org/stable/c/6e7b24c71e530a6c1d656e73d8a30ee081656844
	https://git.kernel.org/stable/c/48c6935a34981bb56f35be0774ec1f30c6e386f8
	https://git.kernel.org/stable/c/1d2f63680c5719a5da92639e981c6c9a87fcee08
	https://git.kernel.org/stable/c/78d20b8c13075eae3d884c21db7a09a6bbdda5b2
	https://git.kernel.org/stable/c/a2a2a6fc2469524caa713036297c542746d148dc