linux-cve-announce - CVE-2025-21951: bus: mhi: host: pci_generic: Use pci_try_reset

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Message-ID: <2025040137-CVE-2025-21951-5e0f@gregkh>
Date: Tue,  1 Apr 2025 16:40:15 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2025-21951: bus: mhi: host: pci_generic: Use pci_try_reset_function() to avoid deadlock

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

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

bus: mhi: host: pci_generic: Use pci_try_reset_function() to avoid deadlock

There are multiple places from where the recovery work gets scheduled
asynchronously. Also, there are multiple places where the caller waits
synchronously for the recovery to be completed. One such place is during
the PM shutdown() callback.

If the device is not alive during recovery_work, it will try to reset the
device using pci_reset_function(). This function internally will take the
device_lock() first before resetting the device. By this time, if the lock
has already been acquired, then recovery_work will get stalled while
waiting for the lock. And if the lock was already acquired by the caller
which waits for the recovery_work to be completed, it will lead to
deadlock.

This is what happened on the X1E80100 CRD device when the device died
before shutdown() callback. Driver core calls the driver's shutdown()
callback while holding the device_lock() leading to deadlock.

And this deadlock scenario can occur on other paths as well, like during
the PM suspend() callback, where the driver core would hold the
device_lock() before calling driver's suspend() callback. And if the
recovery_work was already started, it could lead to deadlock. This is also
observed on the X1E80100 CRD.

So to fix both issues, use pci_try_reset_function() in recovery_work. This
function first checks for the availability of the device_lock() before
trying to reset the device. If the lock is available, it will acquire it
and reset the device. Otherwise, it will return -EAGAIN. If that happens,
recovery_work will fail with the error message "Recovery failed" as not
much could be done.

The Linux kernel CVE team has assigned CVE-2025-21951 to this issue.

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

	Issue introduced in 5.12 with commit 7389337f0a78ea099c47f0af08f64f20c52ab4ba and fixed in 5.15.179 with commit 7746f3bb8917fccb4571a576f3837d80fc513054
	Issue introduced in 5.12 with commit 7389337f0a78ea099c47f0af08f64f20c52ab4ba and fixed in 6.1.131 with commit 7a5ffadd54fe2662f5c99cdccf30144d060376f7
	Issue introduced in 5.12 with commit 7389337f0a78ea099c47f0af08f64f20c52ab4ba and fixed in 6.6.83 with commit 1f9eb7078bc6b5fb5cbfbcb37c4bc01685332b95
	Issue introduced in 5.12 with commit 7389337f0a78ea099c47f0af08f64f20c52ab4ba and fixed in 6.12.19 with commit 985d3cf56d8745ca637deee273929e01df449f85
	Issue introduced in 5.12 with commit 7389337f0a78ea099c47f0af08f64f20c52ab4ba and fixed in 6.13.7 with commit 62505657475c245c9cd46e42ac01026d1e61f027
	Issue introduced in 5.12 with commit 7389337f0a78ea099c47f0af08f64f20c52ab4ba and fixed in 6.14 with commit a321d163de3d8aa38a6449ab2becf4b1581aed96

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-2025-21951
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/bus/mhi/host/pci_generic.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/7746f3bb8917fccb4571a576f3837d80fc513054
	https://git.kernel.org/stable/c/7a5ffadd54fe2662f5c99cdccf30144d060376f7
	https://git.kernel.org/stable/c/1f9eb7078bc6b5fb5cbfbcb37c4bc01685332b95
	https://git.kernel.org/stable/c/985d3cf56d8745ca637deee273929e01df449f85
	https://git.kernel.org/stable/c/62505657475c245c9cd46e42ac01026d1e61f027
	https://git.kernel.org/stable/c/a321d163de3d8aa38a6449ab2becf4b1581aed96