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From: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
To: <syzbot+5f29dc6a889fc42bd896@syzkaller.appspotmail.com>
CC: Nikita Zhandarovich <n.zhandarovich@fintech.ru>,
	<syzkaller-bugs@googlegroups.com>, <linux-kernel@vger.kernel.org>
Subject: Re: [syzbot] WARNING in vmk80xx_auto_attach/usb_submit_urb
Date: Sun, 7 Apr 2024 06:02:03 -0700
Message-ID: <20240407130203.26091-1-n.zhandarovich@fintech.ru>
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Refactor endpoint checks to ensure there is no ambivalence
about endpoint types.

Try a specific branch to mitigate unrelated issues with boot/build.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git fe46a7dd189e
---
 drivers/comedi/drivers/vmk80xx.c | 35 ++++++++++++-----------------------
 1 file changed, 12 insertions(+), 23 deletions(-)

diff --git a/drivers/comedi/drivers/vmk80xx.c b/drivers/comedi/drivers/vmk80xx.c
index 4536ed43f65b..476885403c61 100644
--- a/drivers/comedi/drivers/vmk80xx.c
+++ b/drivers/comedi/drivers/vmk80xx.c
@@ -641,33 +641,22 @@ static int vmk80xx_find_usb_endpoints(struct comedi_device *dev)
 	struct vmk80xx_private *devpriv = dev->private;
 	struct usb_interface *intf = comedi_to_usb_interface(dev);
 	struct usb_host_interface *iface_desc = intf->cur_altsetting;
-	struct usb_endpoint_descriptor *ep_desc;
-	int i;
+	struct usb_endpoint_descriptor *ep_rx_desc, *ep_tx_desc;
+	int i, ret;
 
-	if (iface_desc->desc.bNumEndpoints != 2)
-		return -ENODEV;
-
-	for (i = 0; i < iface_desc->desc.bNumEndpoints; i++) {
-		ep_desc = &iface_desc->endpoint[i].desc;
-
-		if (usb_endpoint_is_int_in(ep_desc) ||
-		    usb_endpoint_is_bulk_in(ep_desc)) {
-			if (!devpriv->ep_rx)
-				devpriv->ep_rx = ep_desc;
-			continue;
-		}
-
-		if (usb_endpoint_is_int_out(ep_desc) ||
-		    usb_endpoint_is_bulk_out(ep_desc)) {
-			if (!devpriv->ep_tx)
-				devpriv->ep_tx = ep_desc;
-			continue;
-		}
-	}
+	if (devpriv->model == VMK8061_MODEL)
+		ret = usb_find_common_endpoints(iface_desc, &ep_rx_desc,
+						&ep_tx_desc, NULL, NULL);
+	else
+		ret = usb_find_common_endpoints(iface_desc, NULL, NULL,
+						&ep_rx_desc, &ep_tx_desc);
 
-	if (!devpriv->ep_rx || !devpriv->ep_tx)
+	if (ret)
 		return -ENODEV;
 
+	devpriv->ep_rx = ep_rx_desc;
+	devpriv->ep_tx = ep_tx_desc;
+
 	if (!usb_endpoint_maxp(devpriv->ep_rx) || !usb_endpoint_maxp(devpriv->ep_tx))
 		return -EINVAL;