CVE-2026-98757: usb: cdns3: fix use-after-free in cdns3_gadget_exit()

CVE-2026-98757: usb: cdns3: fix use-after-free in cdns3_gadget_exit()

[Greg Kroah-Hartman]

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

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

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

usb: cdns3: fix use-after-free in cdns3_gadget_exit()

cdns3_gadget_start() arms two works on system_freezable_wq:
pending_status_wq for the deferred ep0 status stage and aligned_buf_wq
for realigned request buffers. Both handlers use the cdns3_device the
works are embedded in, and cdns3_pending_setup_status_handler() also
calls the ep0 request completion.

cdns3_gadget_exit() does not wait for these works. It frees all
endpoints and aligned buffers and drops the last reference to the
gadget device, which frees priv_dev, so a work queued before the exit
can run after the free.

Fix this by waiting for both works after the gadget driver is unbound
and the IRQ is freed, when no new work can be queued, and before the
endpoints and buffers are released.

This issue was found by an in-house static analysis tool.

The Linux kernel CVE team has assigned CVE-2026-98757 to this issue.


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

	Issue introduced in 5.4 with commit 7733f6c32e36ff9d7adadf40001039bf219b1cbe and fixed in 6.12.113 with commit cc448700db656cceb4b411bf99a2e7132144d035
	Issue introduced in 5.4 with commit 7733f6c32e36ff9d7adadf40001039bf219b1cbe and fixed in 6.18.56 with commit 95160fe606e685ff18de1e6ddcbc08289476004e
	Issue introduced in 5.4 with commit 7733f6c32e36ff9d7adadf40001039bf219b1cbe and fixed in 7.2.10 with commit 159dada48ee2d53eff46e66a8011d67b2c209bbc
	Issue introduced in 5.4 with commit 7733f6c32e36ff9d7adadf40001039bf219b1cbe and fixed in 7.3-rc6 with commit ebe9b68c396792c15d0ac690d592e449e74ed804

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-2026-98757
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/cdns3/cdns3-gadget.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/cc448700db656cceb4b411bf99a2e7132144d035
	https://git.kernel.org/stable/c/95160fe606e685ff18de1e6ddcbc08289476004e
	https://git.kernel.org/stable/c/159dada48ee2d53eff46e66a8011d67b2c209bbc
	https://git.kernel.org/stable/c/ebe9b68c396792c15d0ac690d592e449e74ed804