Re: [PATCH 2/2] HID: check for valid USB device for many HID drivers

[Benjamin Tissoires <benjamin.tissoires@redhat.com>]

On Wed, Dec 1, 2021 at 4:05 PM Benjamin Tissoires <benjamin.tissoires@redhat.com> wrote:
> > > FWIW, I am also working on a test that generates all registered USB
> > > vid/pids from the currently running kernel and will try to inject them
> > > in the testsuite. This should validate this patch and prevent future
> > > mishaps.
> >
> > That would be great to see.  Let me know if you want these broken up
> > smaller, and I will go fix the above issues.
>
> https://gitlab.freedesktop.org/bentiss/hid-tools/-/commit/2b04c6cf46c7405c8a916f324988660cb54dadea
>
> This seems sufficient to make an unpatched kernel scream :)

I have now opened https://gitlab.freedesktop.org/libevdev/hid-tools/-/merge_requests/122
with a quicker solution.

This leads apparently to 2 extra crashes:
- one in hid-holtek-kbd -> hid_is_usb() is called *after* hid_parse(), so
   report_fixup is actually called for uhid devices.
- another in bigbenff which is fixed by the following patch:

---
diff --git a/drivers/hid/hid-bigbenff.c b/drivers/hid/hid-bigbenff.c
index db6da21ade06..74ad8bf98bfd 100644
--- a/drivers/hid/hid-bigbenff.c
+++ b/drivers/hid/hid-bigbenff.c
@@ -191,7 +191,7 @@ static void bigben_worker(struct work_struct *work)
  		struct bigben_device, worker);
  	struct hid_field *report_field = bigben->report->field[0];
  
-	if (bigben->removed)
+	if (bigben->removed || !report_field)
  		return;
  
  	if (bigben->work_led) {
---

Cheers,
Benjamin