From: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
To: John Keeping <john@metanate.com>, linux-usb@vger.kernel.org
Cc: Fabien Chouteau <fabien.chouteau@barco.com>,
Peter Korsgaard <peter.korsgaard@barco.com>,
Felipe Balbi <balbi@ti.com>,
Andrzej Pietrasiewicz <andrzej.p@samsung.com>,
linux-kernel@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Lee Jones <lee@kernel.org>,
Alan Stern <stern@rowland.harvard.edu>
Subject: Re: [PATCH 1/3] usb: gadget: f_hid: fix f_hidg lifetime vs cdev
Date: Wed, 23 Nov 2022 12:52:24 +0100 [thread overview]
Message-ID: <723bd024-121d-dd89-7c39-315e93e49c44@collabora.com> (raw)
In-Reply-To: <20221122123523.3068034-2-john@metanate.com>
Hi John,
W dniu 22.11.2022 o 13:35, John Keeping pisze:
> The embedded struct cdev does not have its lifetime correctly tied to
> the enclosing struct f_hidg, so there is a use-after-free if /dev/hidgN
> is held open while the gadget is deleted.
>
> This can readily be replicated with libusbgx's example programs (for
> conciseness - operating directly via configfs is equivalent):
>
> gadget-hid
> exec 3<> /dev/hidg0
> gadget-vid-pid-remove
> exec 3<&-
>
> Pull the existing device up in to struct f_hidg and make use of the
> cdev_device_{add,del}() helpers. This changes the lifetime of the
> device object to match struct f_hidg, but note that it is still added
> and deleted at the same time.
>
> Fixes: 71adf1189469 ("USB: gadget: add HID gadget driver")
> Signed-off-by: John Keeping <john@metanate.com>
> ---
> drivers/usb/gadget/function/f_hid.c | 52 ++++++++++++++++-------------
> 1 file changed, 28 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/usb/gadget/function/f_hid.c b/drivers/usb/gadget/function/f_hid.c
> index ca0a7d9eaa34..8b8bbeaa27cb 100644
> --- a/drivers/usb/gadget/function/f_hid.c
> +++ b/drivers/usb/gadget/function/f_hid.c
> @@ -71,7 +71,7 @@ struct f_hidg {
> wait_queue_head_t write_queue;
> struct usb_request *req;
>
> - int minor;
> + struct device dev;
> struct cdev cdev;
> struct usb_function func;
>
> @@ -84,6 +84,14 @@ static inline struct f_hidg *func_to_hidg(struct usb_function *f)
> return container_of(f, struct f_hidg, func);
> }
>
> +static void hidg_release(struct device *dev)
> +{
> + struct f_hidg *hidg = container_of(dev, struct f_hidg, dev);
> +
> + kfree(hidg->set_report_buf);
> + kfree(hidg);
> +}
> +
I assume the above is supposed to free the hidg memory as a result of
put_device() and you free two things here ...
> /*-------------------------------------------------------------------------*/
> /* Static descriptors */
>
> @@ -904,9 +912,7 @@ static int hidg_bind(struct usb_configuration *c, struct usb_function *f)
> struct usb_ep *ep;
> struct f_hidg *hidg = func_to_hidg(f);
> struct usb_string *us;
> - struct device *device;
> int status;
> - dev_t dev;
>
> /* maybe allocate device-global string IDs, and patch descriptors */
> us = usb_gstrings_attach(c->cdev, ct_func_strings,
> @@ -999,21 +1005,11 @@ static int hidg_bind(struct usb_configuration *c, struct usb_function *f)
>
> /* create char device */
> cdev_init(&hidg->cdev, &f_hidg_fops);
> - dev = MKDEV(major, hidg->minor);
> - status = cdev_add(&hidg->cdev, dev, 1);
> + status = cdev_device_add(&hidg->cdev, &hidg->dev);
> if (status)
> goto fail_free_descs;
>
> - device = device_create(hidg_class, NULL, dev, NULL,
> - "%s%d", "hidg", hidg->minor);
> - if (IS_ERR(device)) {
> - status = PTR_ERR(device);
> - goto del;
> - }
> -
> return 0;
> -del:
> - cdev_del(&hidg->cdev);
> fail_free_descs:
> usb_free_all_descriptors(f);
> fail:
> @@ -1244,9 +1240,7 @@ static void hidg_free(struct usb_function *f)
>
> hidg = func_to_hidg(f);
> opts = container_of(f->fi, struct f_hid_opts, func_inst);
> - kfree(hidg->report_desc);
> - kfree(hidg->set_report_buf);
> - kfree(hidg);
... while here 3 things used to be freed. What happens to hidg->report_desc?
Regards,
Andrzej
next prev parent reply other threads:[~2022-11-23 11:52 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-22 12:35 [PATCH 0/3] usb: gadget: f_hid: fix f_hidg lifetime vs cdev John Keeping
2022-11-22 12:35 ` [PATCH 1/3] " John Keeping
2022-11-23 11:52 ` Andrzej Pietrasiewicz [this message]
2022-11-23 12:03 ` John Keeping
2022-11-23 12:20 ` Andrzej Pietrasiewicz
2022-11-22 12:35 ` [PATCH 2/3] usb: gadget: f_hid: fix refcount leak on error path John Keeping
2022-11-23 11:55 ` Andrzej Pietrasiewicz
2022-11-23 12:04 ` John Keeping
2022-11-22 12:35 ` [PATCH 3/3] usb: gadget: f_hid: tidy error handling in hidg_alloc John Keeping
2022-11-23 12:19 ` Andrzej Pietrasiewicz
2022-11-22 18:18 ` [PATCH 0/3] usb: gadget: f_hid: fix f_hidg lifetime vs cdev Lee Jones
2022-11-28 14:04 ` Lee Jones
2022-11-28 17:47 ` Greg Kroah-Hartman
2022-11-29 8:59 ` Lee Jones
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