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Fri, 27 Mar 2026 12:24:18 -0700 (PDT) Received: from toolbox ([2a00:1e:8743:9700:a5c1:58f4:f0a9:10cd]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43cf2463dc2sm171956f8f.23.2026.03.27.12.24.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 27 Mar 2026 12:24:17 -0700 (PDT) From: Michael Zimmermann To: Greg Kroah-Hartman Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Michael Zimmermann Subject: [PATCH] usb: gadget: f_hid: don't call cdev_init while cdev in use Date: Fri, 27 Mar 2026 20:22:09 +0100 Message-ID: <20260327192209.59945-1-sigmaepsilon92@gmail.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" When calling unbind, then bind again, cdev_init reinitialized the cdev, even though there may still be references to it. That's the case when the /dev/hidg* device is still opened. This obviously unsafe behavior like oopes. This fixes this by using cdev_alloc to put the cdev on the heap. That way, we can simply allocate a new one in hidg_bind. Closes: https://lore.kernel.org/linux-usb/CAN9vWDKZn0Ts5JyV2_xcAmbnBEi0znML= g_USMFrShRryXrgWGQ@mail.gmail.com/T/#m2cb0dba3633b67b2a679c98499508267d1508= 881 Signed-off-by: Michael Zimmermann --- drivers/usb/gadget/function/f_hid.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/drivers/usb/gadget/function/f_hid.c b/drivers/usb/gadget/funct= ion/f_hid.c index 8812ebf33d14..66be2e1282c1 100644 --- a/drivers/usb/gadget/function/f_hid.c +++ b/drivers/usb/gadget/function/f_hid.c @@ -106,7 +106,7 @@ struct f_hidg { struct list_head report_list; =20 struct device dev; - struct cdev cdev; + struct cdev *cdev; struct usb_function func; =20 struct usb_ep *in_ep; @@ -749,8 +749,9 @@ static int f_hidg_release(struct inode *inode, struct f= ile *fd) =20 static int f_hidg_open(struct inode *inode, struct file *fd) { + struct kobject *parent =3D inode->i_cdev->kobj.parent; struct f_hidg *hidg =3D - container_of(inode->i_cdev, struct f_hidg, cdev); + container_of(parent, struct f_hidg, dev.kobj); =20 fd->private_data =3D hidg; =20 @@ -1285,8 +1286,12 @@ static int hidg_bind(struct usb_configuration *c, st= ruct usb_function *f) } =20 /* create char device */ - cdev_init(&hidg->cdev, &f_hidg_fops); - status =3D cdev_device_add(&hidg->cdev, &hidg->dev); + hidg->cdev =3D cdev_alloc(); + if (!hidg->cdev) + goto fail_free_all; + hidg->cdev->ops =3D &f_hidg_fops; + + status =3D cdev_device_add(hidg->cdev, &hidg->dev); if (status) goto fail_free_all; =20 @@ -1588,7 +1593,7 @@ static void hidg_unbind(struct usb_configuration *c, = struct usb_function *f) { struct f_hidg *hidg =3D func_to_hidg(f); =20 - cdev_device_del(&hidg->cdev, &hidg->dev); + cdev_device_del(hidg->cdev, &hidg->dev); destroy_workqueue(hidg->workqueue); usb_free_all_descriptors(f); } --=20 2.53.0