CVE-2026-64478: ALSA: usb-audio: avoid kobject path lookup in DualSense match

From: Greg Kroah-Hartman <[email protected]>

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

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

ALSA: usb-audio: avoid kobject path lookup in DualSense match

The DualSense jack-detection input handler verifies that a matching input
device belongs to the same physical controller by building kobject path
strings for both the input device and the USB audio device, then comparing
the path prefix.

This was observed when a weak physical connection caused the controller
to rapidly disconnect and reconnect. During that repeated hotplug,
snd_dualsense_ih_match() can run while the controller's USB device is
being disconnected. kobject_get_path() walks ancestor kobjects and
dereferences their names; if the USB device kobject name is no longer
valid, this can fault in strlen():

  RIP: 0010:strlen+0x10/0x30
  Call Trace:
   kobject_get_path+0x34/0x150
   snd_dualsense_ih_match+0x49/0xd0 [snd_usb_audio]
   input_register_device+0x566/0x6a0
   ps_probe+0xb89/0x1590 [hid_playstation]

The same ownership check can be done without building kobject path
strings. The input device is parented below the HID device, USB interface
and USB device, so walking the input device parent chain and comparing
against the mixer USB device preserves the check without dereferencing
kobject names during disconnect.

The Linux kernel CVE team has assigned CVE-2026-64478 to this issue.


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

	Issue introduced in 5.10.245 with commit d0b0264009596c07a77d82808b0dae72bc04ac5c and fixed in 5.10.261 with commit e4c66a149c408e44e60bfec3fabf08b6b7abbc60
	Issue introduced in 5.15.194 with commit b4b94f092f193d7a2db8e82af5e51519ae89963c and fixed in 5.15.212 with commit 4566bf8ae9dbfe81bdc2ff1702d59db8a233b06e
	Issue introduced in 6.1.155 with commit c2d5b0a6c688ffb32c35627e337fbbcc65bc275f and fixed in 6.1.178 with commit 662a1d7b5affc424ea4f4bc20dd99be29e687886
	Issue introduced in 6.6.109 with commit d04d301614630724feb4048bf17432fc7964fe74 and fixed in 6.6.145 with commit a47ecd904c51ae6a42957feb3cf2f4266adee2e5
	Issue introduced in 6.12.50 with commit a705899ec6085b12a33aa0fd94a58e82e9e90502 and fixed in 6.12.96 with commit c1da6d3f45036fa63672ee04ad97cb526b40b987
	Issue introduced in 6.17 with commit 79d561c4ec0497669f19a9550cfb74812f60938b and fixed in 6.18.39 with commit a263eb12cbe2e208e6e637df0f9b0be9a484158e
	Issue introduced in 6.17 with commit 79d561c4ec0497669f19a9550cfb74812f60938b and fixed in 7.1.4 with commit 4246dd043b7a4f8e3bc1d2896e81d11220610eda
	Issue introduced in 6.17 with commit 79d561c4ec0497669f19a9550cfb74812f60938b and fixed in 7.2-rc1 with commit 7693c0cc415f3a16a7a3355f245474a5e661be4e
	Issue introduced in 5.4.300 with commit 104ad9bae11ee450fb7d0595ff7876cfb6527838
	Issue introduced in 6.16.10 with commit 0105cfc41abeb428d4405951a20e1e239bea5e1d

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-2026-64478
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:
	sound/usb/mixer_quirks.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/e4c66a149c408e44e60bfec3fabf08b6b7abbc60
	https://git.kernel.org/stable/c/4566bf8ae9dbfe81bdc2ff1702d59db8a233b06e
	https://git.kernel.org/stable/c/662a1d7b5affc424ea4f4bc20dd99be29e687886
	https://git.kernel.org/stable/c/a47ecd904c51ae6a42957feb3cf2f4266adee2e5
	https://git.kernel.org/stable/c/c1da6d3f45036fa63672ee04ad97cb526b40b987
	https://git.kernel.org/stable/c/a263eb12cbe2e208e6e637df0f9b0be9a484158e
	https://git.kernel.org/stable/c/4246dd043b7a4f8e3bc1d2896e81d11220610eda
	https://git.kernel.org/stable/c/7693c0cc415f3a16a7a3355f245474a5e661be4e