fbdev: udlfb: Fix endpoint check

In the Linux kernel, the following vulnerability has been resolved:

fbdev: udlfb: Fix endpoint check

The syzbot fuzzer detected a problem in the udlfb driver, caused by an

endpoint not having the expected type:

usb 1-1: Read EDID byte 0 failed: -71

usb 1-1: Unable to get valid EDID from device/display

------------[ cut here ]------------

usb 1-1: BOGUS urb xfer, pipe 3 != type 1

WARNING: CPU: 0 PID: 9 at drivers/usb/core/urb.c:504 usb_submit_urb+0xed6/0x1880

drivers/usb/core/urb.c:504

Modules linked in:

CPU: 0 PID: 9 Comm: kworker/0:1 Not tainted

6.4.0-rc1-syzkaller-00016-ga4422ff22142 #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google

04/28/2023

Workqueue: usb_hub_wq hub_event

RIP: 0010:usb_submit_urb+0xed6/0x1880 drivers/usb/core/urb.c:504

...

Call Trace:

<TASK>

dlfb_submit_urb+0x92/0x180 drivers/video/fbdev/udlfb.c:1980

dlfb_set_video_mode+0x21f0/0x2950 drivers/video/fbdev/udlfb.c:315

dlfb_ops_set_par+0x2a7/0x8d0 drivers/video/fbdev/udlfb.c:1111

dlfb_usb_probe+0x149a/0x2710 drivers/video/fbdev/udlfb.c:1743

The current approach for this issue failed to catch the problem

because it only checks for the existence of a bulk-OUT endpoint; it

doesn't check whether this endpoint is the one that the driver will

actually use.

We can fix the problem by instead checking that the endpoint used by

the driver does exist and is bulk-OUT.