Re: [PATCH net] r8152: check the informaton of the device

Verify some fields of the USB descriptor to make sure the driver
could be used by the device.

BugLink: https://syzkaller.appspot.com/bug?id=912c9c373656996801b4de61f1e3cb326fe940aa
Reported-by: syzbot+95afd23673f5dd295c57@syzkaller.appspotmail.com
Fixes: c2198943e33b ("r8152: search the configuration of vendor mode")
Signed-off-by: Hayes Wang <redacted>
---
 drivers/net/usb/r8152.c | 71 +++++++++++++++++++++++++++++++++++++++--
 1 file changed, 69 insertions(+), 2 deletions(-)

diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c
index 136ea06540ff..f348350f5da1 100644
--- a/drivers/net/usb/r8152.c
+++ b/drivers/net/usb/r8152.c

@@ -8107,6 +8107,69 @@ static void r8156b_init(struct r8152 *tp)
 	tp->coalesce = 15000;	/* 15 us */
 }
 
+static bool rtl_check_vendor_ok(struct usb_interface *intf)
+{
+	struct usb_host_interface *alt = intf->cur_altsetting;
+	struct usb_host_endpoint *in = NULL, *out = NULL, *intr = NULL;
+	unsigned int ep;
+
+	if (alt->desc.bNumEndpoints < 3) {
+		dev_err(&intf->dev, "Unexpected bNumEndpoints %d\n", alt->desc.bNumEndpoints);
+		return false;
+	}
+
+	for (ep = 0; ep < alt->desc.bNumEndpoints; ep++) {
+		struct usb_host_endpoint *e;
+
+		e = alt->endpoint + ep;
+
+		/* ignore endpoints which cannot transfer data */
+		if (!usb_endpoint_maxp(&e->desc))
+			continue;
+
+		switch (e->desc.bmAttributes) {
+		case USB_ENDPOINT_XFER_INT:
+			if (!usb_endpoint_dir_in(&e->desc))
+				continue;
+			if (!intr)
+				intr = e;
+			break;
+		case USB_ENDPOINT_XFER_BULK:
+			if (usb_endpoint_dir_in(&e->desc)) {
+				if (!in)
+					in = e;
+			} else if (!out) {
+				out = e;
+			}
+			break;
+		default:
+			continue;
+		}
+	}
+
+	if (!in || !out || !intr) {
+		dev_err(&intf->dev, "Miss Endpoints\n");
+		return false;
+	}
+
+	if ((in->desc.bEndpointAddress & USB_ENDPOINT_NUMBER_MASK) != 1) {
+		dev_err(&intf->dev, "Invalid Rx Endpoints\n");
+		return false;
+	}
+
+	if ((out->desc.bEndpointAddress & USB_ENDPOINT_NUMBER_MASK) != 2) {
+		dev_err(&intf->dev, "Invalid Tx Endpoints\n");
+		return false;
+	}
+
+	if ((intr->desc.bEndpointAddress & USB_ENDPOINT_NUMBER_MASK) != 3) {
+		dev_err(&intf->dev, "Invalid interrupt Endpoints\n");
+		return false;
+	}
+
+	return true;
+}