Re: [PATCH v3] HID: add driver for U2F Zero built-in LED and RNG

From: Andrej Shadura <andrew.shadura@collabora.co.uk>
To: Jiri Kosina <jikos@kernel.org>
Cc: Benjamin Tissoires <benjamin.tissoires@gmail.com>,
	linux-input <linux-input@vger.kernel.org>,
	linux-usb@vger.kernel.org,
	Andrzej Pietrasiewicz <andrzej.p@collabora.com>,
	kernel@collabora.com, linux-crypto@vger.kernel.org
Subject: Re: [PATCH v3] HID: add driver for U2F Zero built-in LED and RNG
Date: Wed, 17 Apr 2019 16:47:54 +0200	[thread overview]
Message-ID: <3d07beba-2cd7-8d84-947e-095897fb3e0c@collabora.co.uk> (raw)
In-Reply-To: <nycvar.YFH.7.76.1904171642020.9803@cbobk.fhfr.pm>

On 17/04/2019 16:43, Jiri Kosina wrote:
> On Thu, 11 Apr 2019, Andrej Shadura wrote:
> 
>>>>> So I still am not really happy about this being wired up into generic HID
>>>>> although it's really a USB driver, but we've discussed that already, and I
>>>>> don't see any option that'd work substantially better in this case,
>>>>> especially from the UX point of view. Oh well. Applied to for-5.2/u2fzero,
>>>>> thanks!
>>>>>
>>>>
>>>> Hi wish I were CC-ed on these threads.
>>>
>>> Gah, for some reason I was convinced you were.
>>>
>>>> My CI script now fails because hid-u2fzero.ko needs devm_hwrng_register 
>>>> and the Kconfig doesn't force pulling the right dependency.
>>
>>>> Also, you probably want to add in .probe() a check for the actual 
>>>> transport driver (`hid_is_using_ll_driver(hdev, &usb_hid_driver)`) or 
>>>> you can not use the usbhid functions without crashing the kernel.
>>
>> Thanks, that’s very useful.
>>
>>> Benjamin, I love your CI :)
>>>
>>> Andrej, could you please send fixups on top of the applied patch?
>>
>> Sure, will do.
> 
> I didn't receive any followup; the Kconfig dependency has already been 
> fixed by Mao Wenan, and I've just queued the patch below on top of that as 
> well.

Sorry, I’ve had too much on my plate in the recent days, so I’ve
unfortunately been pushing this task off a bit. Thanks to both of you,
Mao and Jiří, both things should have really been done by me. I’ll try
to get those things right from the beginning the next time.

> From: Jiri Kosina <jkosina@suse.cz>
> Subject: [PATCH] HID: u2fzero: fail probe if not using USB transport
> 
> u2fzero driver is USB-only. Therefore we have to give up in ->probe()
> callback in case we're called with non-USB transport driver bound,
> otherwise the kernel will crash trying to use USBHID API on a non-USB
> transport.
> 
> Fixes: 42337b9d4d958("HID: add driver for U2F Zero built-in LED and RNG")
> Reported-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
> ---
>  drivers/hid/hid-u2fzero.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/hid/hid-u2fzero.c b/drivers/hid/hid-u2fzero.c
> index d11a5cb56a0d..95e0807878c7 100644
> --- a/drivers/hid/hid-u2fzero.c
> +++ b/drivers/hid/hid-u2fzero.c
> @@ -286,6 +286,9 @@ static int u2fzero_probe(struct hid_device *hdev,
>  	unsigned int minor;
>  	int ret;
>  
> +	if (!hid_is_using_ll_driver(hdev, &usb_hid_driver))
> +		return -EINVAL;
> +
>  	dev = devm_kzalloc(&hdev->dev, sizeof(*dev), GFP_KERNEL);
>  	if (dev == NULL)
>  		return -ENOMEM;
> 

-- 
Cheers,
  Andrej