Message-ID: <2025061844-CVE-2025-38016-2aee@gregkh>
Date: Wed, 18 Jun 2025 11:28:50 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-38016: HID: bpf: abort dispatch if device destroyed

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

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

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

HID: bpf: abort dispatch if device destroyed

The current HID bpf implementation assumes no output report/request will
go through it after hid_bpf_destroy_device() has been called. This leads
to a bug that unplugging certain types of HID devices causes a cleaned-
up SRCU to be accessed. The bug was previously a hidden failure until a
recent x86 percpu change [1] made it access not-present pages.

The bug will be triggered if the conditions below are met:

A) a device under the driver has some LEDs on
B) hid_ll_driver->request() is uninplemented (e.g., logitech-djreceiver)

If condition A is met, hidinput_led_worker() is always scheduled *after*
hid_bpf_destroy_device().

hid_destroy_device
` hid_bpf_destroy_device
  ` cleanup_srcu_struct(&hdev->bpf.srcu)
` hid_remove_device
  ` ...
    ` led_classdev_unregister
      ` led_trigger_set(led_cdev, NULL)
        ` led_set_brightness(led_cdev, LED_OFF)
          ` ...
            ` input_inject_event
              ` input_event_dispose
                ` hidinput_input_event
                  ` schedule_work(&hid->led_work) [hidinput_led_worker]

This is fine when condition B is not met, where hidinput_led_worker()
calls hid_ll_driver->request(). This is the case for most HID drivers,
which implement it or use the generic one from usbhid. The driver itself
or an underlying driver will then abort processing the request.

Otherwise, hidinput_led_worker() tries hid_hw_output_report() and leads
to the bug.

hidinput_led_worker
` hid_hw_output_report
  ` dispatch_hid_bpf_output_report
    ` srcu_read_lock(&hdev->bpf.srcu)
    ` srcu_read_unlock(&hdev->bpf.srcu, idx)

The bug has existed since the introduction [2] of
dispatch_hid_bpf_output_report(). However, the same bug also exists in
dispatch_hid_bpf_raw_requests(), and I've reproduced (no visible effect
because of the lack of [1], but confirmed bpf.destroyed == 1) the bug
against the commit (i.e., the Fixes:) introducing the function. This is
because hidinput_led_worker() falls back to hid_hw_raw_request() when
hid_ll_driver->output_report() is uninplemented (e.g., logitech-
djreceiver).

hidinput_led_worker
` hid_hw_output_report: -ENOSYS
` hid_hw_raw_request
  ` dispatch_hid_bpf_raw_requests
    ` srcu_read_lock(&hdev->bpf.srcu)
    ` srcu_read_unlock(&hdev->bpf.srcu, idx)

Fix the issue by returning early in the two mentioned functions if
hid_bpf has been marked as destroyed. Though
dispatch_hid_bpf_device_event() handles input events, and there is no
evidence that it may be called after the destruction, the same check, as
a safety net, is also added to it to maintain the consistency among all
dispatch functions.

The impact of the bug on other architectures is unclear. Even if it acts
as a hidden failure, this is still dangerous because it corrupts
whatever is on the address calculated by SRCU. Thus, CC'ing the stable
list.

[1]: commit 9d7de2aa8b41 ("x86/percpu/64: Use relative percpu offsets")
[2]: commit 9286675a2aed ("HID: bpf: add HID-BPF hooks for
hid_hw_output_report")

The Linux kernel CVE team has assigned CVE-2025-38016 to this issue.


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

	Issue introduced in 6.11 with commit 8bd0488b5ea58655ad6fdcbe0408ef49b16882b1 and fixed in 6.12.30 with commit f8544be7e8e55b0ef23e1ab90e23e8d4d4aad3d3
	Issue introduced in 6.11 with commit 8bd0488b5ea58655ad6fdcbe0408ef49b16882b1 and fixed in 6.14.8 with commit e4b4fe25a4101d1ddb5884f40e149a3618983b66
	Issue introduced in 6.11 with commit 8bd0488b5ea58655ad6fdcbe0408ef49b16882b1 and fixed in 6.15 with commit 578e1b96fad7402ff7e9c7648c8f1ad0225147c8

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-2025-38016
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/hid/bpf/hid_bpf_dispatch.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/f8544be7e8e55b0ef23e1ab90e23e8d4d4aad3d3
	https://git.kernel.org/stable/c/e4b4fe25a4101d1ddb5884f40e149a3618983b66
	https://git.kernel.org/stable/c/578e1b96fad7402ff7e9c7648c8f1ad0225147c8

Powered by blists - more mailing lists