linux-cve-announce - CVE-2025-40094: usb: gadget: f_acm: Refactor bind path to use _

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Message-ID: <2025103016-CVE-2025-40094-113d@gregkh>
Date: Thu, 30 Oct 2025 10:48:21 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-40094: usb: gadget: f_acm: Refactor bind path to use __free()

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

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

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

usb: gadget: f_acm: Refactor bind path to use __free()

After an bind/unbind cycle, the acm->notify_req is left stale. If a
subsequent bind fails, the unified error label attempts to free this
stale request, leading to a NULL pointer dereference when accessing
ep->ops->free_request.

Refactor the error handling in the bind path to use the __free()
automatic cleanup mechanism.

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000020
Call trace:
 usb_ep_free_request+0x2c/0xec
 gs_free_req+0x30/0x44
 acm_bind+0x1b8/0x1f4
 usb_add_function+0xcc/0x1f0
 configfs_composite_bind+0x468/0x588
 gadget_bind_driver+0x104/0x270
 really_probe+0x190/0x374
 __driver_probe_device+0xa0/0x12c
 driver_probe_device+0x3c/0x218
 __device_attach_driver+0x14c/0x188
 bus_for_each_drv+0x10c/0x168
 __device_attach+0xfc/0x198
 device_initial_probe+0x14/0x24
 bus_probe_device+0x94/0x11c
 device_add+0x268/0x48c
 usb_add_gadget+0x198/0x28c
 dwc3_gadget_init+0x700/0x858
 __dwc3_set_mode+0x3cc/0x664
 process_scheduled_works+0x1d8/0x488
 worker_thread+0x244/0x334
 kthread+0x114/0x1bc
 ret_from_fork+0x10/0x20

The Linux kernel CVE team has assigned CVE-2025-40094 to this issue.


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

	Issue introduced in 2.6.27 with commit 1f1ba11b64947051fc32aa15fcccef6463b433f7 and fixed in 5.15.196 with commit c5d116862dd3ed162d079738a5ebddf9fceea850
	Issue introduced in 2.6.27 with commit 1f1ba11b64947051fc32aa15fcccef6463b433f7 and fixed in 6.1.158 with commit 2b1546f7c5fc6c44555a8e7a2b34229d1dcd2175
	Issue introduced in 2.6.27 with commit 1f1ba11b64947051fc32aa15fcccef6463b433f7 and fixed in 6.6.114 with commit e348d18fb0124b662cfefb3001733b49da428215
	Issue introduced in 2.6.27 with commit 1f1ba11b64947051fc32aa15fcccef6463b433f7 and fixed in 6.12.55 with commit 201a66d8e6630762e760e1d78f1d149da1691e7b
	Issue introduced in 2.6.27 with commit 1f1ba11b64947051fc32aa15fcccef6463b433f7 and fixed in 6.17.5 with commit c4301e4dd6b32faccb744f1c2320e64235b68d3b
	Issue introduced in 2.6.27 with commit 1f1ba11b64947051fc32aa15fcccef6463b433f7 and fixed in 6.18-rc1 with commit 47b2116e54b4a854600341487e8b55249e926324

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-2025-40094
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/function/f_acm.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/c5d116862dd3ed162d079738a5ebddf9fceea850
	https://git.kernel.org/stable/c/2b1546f7c5fc6c44555a8e7a2b34229d1dcd2175
	https://git.kernel.org/stable/c/e348d18fb0124b662cfefb3001733b49da428215
	https://git.kernel.org/stable/c/201a66d8e6630762e760e1d78f1d149da1691e7b
	https://git.kernel.org/stable/c/c4301e4dd6b32faccb744f1c2320e64235b68d3b
	https://git.kernel.org/stable/c/47b2116e54b4a854600341487e8b55249e926324