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From:   Pavel Skripkin <paskripkin@gmail.com>
To:     dmitry.torokhov@gmail.com, vdronov@redhat.com
Cc:     linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
        Pavel Skripkin <paskripkin@gmail.com>,
        syzbot+75cccf2b7da87fb6f84b@syzkaller.appspotmail.com
Subject: [PATCH] Input: aiptek - properly check endpoint type
Date:   Tue,  8 Mar 2022 22:43:28 +0300
Message-Id: <20220308194328.26220-1-paskripkin@gmail.com>
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Syzbot reported warning in usb_submit_urb() which is caused by wrong
endpoint type. There was a check for the number of endpoints, but not
for the type of endpoint.

Fix it by replacing old desc.bNumEndpoints check with
usb_find_common_endpoints() helper for finding endpoints

Fail log:

usb 5-1: BOGUS urb xfer, pipe 1 != type 3
WARNING: CPU: 2 PID: 48 at drivers/usb/core/urb.c:502 usb_submit_urb+0xed2/0x18a0 drivers/usb/core/urb.c:502
Modules linked in:
CPU: 2 PID: 48 Comm: kworker/2:2 Not tainted 5.17.0-rc6-syzkaller-00226-g07ebd38a0da2 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
Workqueue: usb_hub_wq hub_event
...
Call Trace:
 <TASK>
 aiptek_open+0xd5/0x130 drivers/input/tablet/aiptek.c:830
 input_open_device+0x1bb/0x320 drivers/input/input.c:629
 kbd_connect+0xfe/0x160 drivers/tty/vt/keyboard.c:1593

Fixes: 8e20cf2bce12 ("Input: aiptek - fix crash on detecting device without endpoints")
Reported-and-tested-by: syzbot+75cccf2b7da87fb6f84b@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
---
 drivers/input/tablet/aiptek.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/input/tablet/aiptek.c b/drivers/input/tablet/aiptek.c
index fcb1b646436a..5d0dc277bf86 100644
--- a/drivers/input/tablet/aiptek.c
+++ b/drivers/input/tablet/aiptek.c
@@ -1787,15 +1787,12 @@ aiptek_probe(struct usb_interface *intf, const struct usb_device_id *id)
 	input_set_abs_params(inputdev, ABS_TILT_Y, AIPTEK_TILT_MIN, AIPTEK_TILT_MAX, 0, 0);
 	input_set_abs_params(inputdev, ABS_WHEEL, AIPTEK_WHEEL_MIN, AIPTEK_WHEEL_MAX - 1, 0, 0);
 
-	/* Verify that a device really has an endpoint */
-	if (intf->cur_altsetting->desc.bNumEndpoints < 1) {
+	err = usb_find_common_endpoints(intf->cur_altsetting, NULL, NULL, &endpoint, NULL);
+	if (err) {
 		dev_err(&intf->dev,
-			"interface has %d endpoints, but must have minimum 1\n",
-			intf->cur_altsetting->desc.bNumEndpoints);
-		err = -EINVAL;
+			"interface has no int in endpoints, but must have minimum 1\n");
 		goto fail3;
 	}
-	endpoint = &intf->cur_altsetting->endpoint[0].desc;
 
 	/* Go set up our URB, which is called when the tablet receives
 	 * input.
-- 
2.35.1