Date:   Wed, 17 Apr 2019 16:43:17 +0200 (CEST)
From:   Jiri Kosina <jikos@kernel.org>
To:     Andrej Shadura <andrew.shadura@collabora.co.uk>
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
In-Reply-To: <d33b8772-bae6-1d20-8ff0-3397095f6e4b@collabora.co.uk>
Message-ID: <nycvar.YFH.7.76.1904171642020.9803@cbobk.fhfr.pm>
References: <20190401124200.17331-1-andrew.shadura@collabora.co.uk> <nycvar.YFH.7.76.1904101400520.9803@cbobk.fhfr.pm> <CAN+gG=H6TGtB68-XJ+Pg53EhL_M2m8MG1z33Yenvd9PhXJ=Oqw@mail.gmail.com> <nycvar.YFH.7.76.1904111234080.9803@cbobk.fhfr.pm>
 <d33b8772-bae6-1d20-8ff0-3397095f6e4b@collabora.co.uk>
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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.


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;

-- 
Jiri Kosina
SUSE Labs