linux-cve-announce - CVE-2022-50704: USB: gadget: Fix use-after-free during usb config switch

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Message-ID: <2025122419-CVE-2022-50704-ca2b@gregkh>
Date: Wed, 24 Dec 2025 11:56:21 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2022-50704: USB: gadget: Fix use-after-free during usb config switch

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

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

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

USB: gadget: Fix use-after-free during usb config switch

In the process of switching USB config from rndis to other config,
if the hardware does not support the ->pullup callback, or the
hardware encounters a low probability fault, both of them may cause
the ->pullup callback to fail, which will then cause a system panic
(use after free).

The gadget drivers sometimes need to be unloaded regardless of the
hardware's behavior.

Analysis as follows:
=======================================================================
(1) write /config/usb_gadget/g1/UDC "none"

gether_disconnect+0x2c/0x1f8
rndis_disable+0x4c/0x74
composite_disconnect+0x74/0xb0
configfs_composite_disconnect+0x60/0x7c
usb_gadget_disconnect+0x70/0x124
usb_gadget_unregister_driver+0xc8/0x1d8
gadget_dev_desc_UDC_store+0xec/0x1e4

(2) rm /config/usb_gadget/g1/configs/b.1/f1

rndis_deregister+0x28/0x54
rndis_free+0x44/0x7c
usb_put_function+0x14/0x1c
config_usb_cfg_unlink+0xc4/0xe0
configfs_unlink+0x124/0x1c8
vfs_unlink+0x114/0x1dc

(3) rmdir /config/usb_gadget/g1/functions/rndis.gs4

panic+0x1fc/0x3d0
do_page_fault+0xa8/0x46c
do_mem_abort+0x3c/0xac
el1_sync_handler+0x40/0x78
0xffffff801138f880
rndis_close+0x28/0x34
eth_stop+0x74/0x110
dev_close_many+0x48/0x194
rollback_registered_many+0x118/0x814
unregister_netdev+0x20/0x30
gether_cleanup+0x1c/0x38
rndis_attr_release+0xc/0x14
kref_put+0x74/0xb8
configfs_rmdir+0x314/0x374

If gadget->ops->pullup() return an error, function rndis_close() will be
called, then it will causes a use-after-free problem.
=======================================================================

The Linux kernel CVE team has assigned CVE-2022-50704 to this issue.


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

	Issue introduced in 4.20 with commit 0a55187a1ec8c03d0619e7ce41d10fdc39cff036 and fixed in 6.0.16 with commit 30e926aa835ac2e6ad05822e4cb75833feb0d99f
	Issue introduced in 4.20 with commit 0a55187a1ec8c03d0619e7ce41d10fdc39cff036 and fixed in 6.1.2 with commit 99a58ac42d9b6911834b0224b6782aea0c311346
	Issue introduced in 4.20 with commit 0a55187a1ec8c03d0619e7ce41d10fdc39cff036 and fixed in 6.2 with commit afdc12887f2b2ecf20d065a7d81ad29824155083

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-2022-50704
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/30e926aa835ac2e6ad05822e4cb75833feb0d99f
	https://git.kernel.org/stable/c/99a58ac42d9b6911834b0224b6782aea0c311346
	https://git.kernel.org/stable/c/afdc12887f2b2ecf20d065a7d81ad29824155083