CVE-2026-93080: firmware: arm_scmi: Fix transport device teardown lookup

CVE-2026-93080: firmware: arm_scmi: Fix transport device teardown lookup

[Greg Kroah-Hartman]

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

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

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

firmware: arm_scmi: Fix transport device teardown lookup

SCMI transport devices are deliberately excluded from normal SCMI bus
matching so protocol drivers cannot bind to the internal transport
children. However, scmi_device_destroy() uses the same protocol/name
lookup to find devices that must be unregistered during channel teardown.

Split the match helper so driver matching still skips transport devices,
while explicit child lookup can find them for teardown. Use a shared
transport-device name prefix macro for both matching and name generation.

Since transport-device names are derived from direction and protocol ID,
reject duplicate protocol channel setup before creating or finding a
transport device. This prevents malformed firmware with duplicate
protocol child nodes from reusing an existing transport device and then
destroying it when the duplicate IDR insertion fails.

The Linux kernel CVE team has assigned CVE-2026-93080 to this issue.


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

	Issue introduced in 6.16 with commit 9593804c44c24545e1b0496786dcb765d7b0e193 and fixed in 6.18.52 with commit c656427440ea627166394d00c4b72147d5d79c60
	Issue introduced in 6.16 with commit 9593804c44c24545e1b0496786dcb765d7b0e193 and fixed in 7.2.6 with commit 4635953b4c1af477e166073521a77de6279f6929
	Issue introduced in 6.16 with commit 9593804c44c24545e1b0496786dcb765d7b0e193 and fixed in 7.3-rc1 with commit a14dd8fe0a95db638c550ed984cfe2a7428c783d

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-2026-93080
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/firmware/arm_scmi/bus.c
	drivers/firmware/arm_scmi/common.h
	drivers/firmware/arm_scmi/driver.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/c656427440ea627166394d00c4b72147d5d79c60
	https://git.kernel.org/stable/c/4635953b4c1af477e166073521a77de6279f6929
	https://git.kernel.org/stable/c/a14dd8fe0a95db638c550ed984cfe2a7428c783d