linux-cve-announce - CVE-2025-21838: usb: gadget: core: flush gadget workqueue after device removal

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Message-ID: <2025030706-CVE-2025-21838-5ade@gregkh>
Date: Fri,  7 Mar 2025 10:10:08 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2025-21838: usb: gadget: core: flush gadget workqueue after device removal

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

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

usb: gadget: core: flush gadget workqueue after device removal

device_del() can lead to new work being scheduled in gadget->work
workqueue. This is observed, for example, with the dwc3 driver with the
following call stack:
  device_del()
    gadget_unbind_driver()
      usb_gadget_disconnect_locked()
        dwc3_gadget_pullup()
	  dwc3_gadget_soft_disconnect()
	    usb_gadget_set_state()
	      schedule_work(&gadget->work)

Move flush_work() after device_del() to ensure the workqueue is cleaned
up.

The Linux kernel CVE team has assigned CVE-2025-21838 to this issue.


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

	Issue introduced in 3.12 with commit 5702f75375aa9ecf8ad3431aef3fe6ce8c8dbd15 and fixed in 6.6.80 with commit 859cb45aefa6de823b2fa7f229fe6d9562c9f3b7
	Issue introduced in 3.12 with commit 5702f75375aa9ecf8ad3431aef3fe6ce8c8dbd15 and fixed in 6.12.16 with commit f894448f3904d7ad66fecef8f01fe0172629e091
	Issue introduced in 3.12 with commit 5702f75375aa9ecf8ad3431aef3fe6ce8c8dbd15 and fixed in 6.13.4 with commit 97695b5a1b5467a4f91194db12160f56da445dfe
	Issue introduced in 3.12 with commit 5702f75375aa9ecf8ad3431aef3fe6ce8c8dbd15 and fixed in 6.14-rc3 with commit 399a45e5237ca14037120b1b895bd38a3b4492ea

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-2025-21838
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/usb/gadget/udc/core.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/859cb45aefa6de823b2fa7f229fe6d9562c9f3b7
	https://git.kernel.org/stable/c/f894448f3904d7ad66fecef8f01fe0172629e091
	https://git.kernel.org/stable/c/97695b5a1b5467a4f91194db12160f56da445dfe
	https://git.kernel.org/stable/c/399a45e5237ca14037120b1b895bd38a3b4492ea