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

[Jiri Kosina <jikos@kernel.org>]

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