linux-kernel - [PATCH v2] ar5523: check endpoints type and direction in probe()

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Message-Id: <20220823225754.519945-1-mazinalhaddad05@gmail.com>
Date:   Wed, 24 Aug 2022 01:57:54 +0300
From:   Mazin Al Haddad <mazinalhaddad05@...il.com>
To:     pontus.fuchs@...il.com
Cc:     kvalo@...nel.org, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        skhan@...uxfoundation.org, paskripkin@...il.com,
        Mazin Al Haddad <mazinalhaddad05@...il.com>,
        syzbot+1bc2c2afd44f820a669f@...kaller.appspotmail.com
Subject: [PATCH v2] ar5523: check endpoints type and direction in probe()

Fixes a bug reported by syzbot, where a warning occurs in usb_submit_urb()
due to the wrong endpoint type. There is no check for both the number
of endpoints and the type which causes an error as the code tries to
send a URB to the wrong endpoint.

Fix it by adding a check for the number of endpoints and the
direction/type of the endpoints. If the endpoints do not match the
expected configuration -ENODEV is returned.

Syzkaller report:

usb 1-1: BOGUS urb xfer, pipe 3 != type 1
WARNING: CPU: 1 PID: 71 at drivers/usb/core/urb.c:502 usb_submit_urb+0xed2/0x18a0 drivers/usb/core/urb.c:502
Modules linked in:
CPU: 1 PID: 71 Comm: kworker/1:2 Not tainted 5.19.0-rc7-syzkaller-00150-g32f02a211b0a #0
Hardware name: Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022
Workqueue: usb_hub_wq hub_event
Call Trace:
 <TASK>
 ar5523_cmd+0x420/0x790 drivers/net/wireless/ath/ar5523/ar5523.c:275
 ar5523_cmd_read drivers/net/wireless/ath/ar5523/ar5523.c:302 [inline]
 ar5523_host_available drivers/net/wireless/ath/ar5523/ar5523.c:1376 [inline]
 ar5523_probe+0xc66/0x1da0 drivers/net/wireless/ath/ar5523/ar5523.c:1655

Link: https://syzkaller.appspot.com/bug?extid=1bc2c2afd44f820a669f
Reported-and-tested-by: syzbot+1bc2c2afd44f820a669f@...kaller.appspotmail.com
Signed-off-by: Mazin Al Haddad <mazinalhaddad05@...il.com>
---
v1->v2 changes:
	- Fix incorrect check in if statement within switch case (was missing
		a "!" operator).
	- Added comments explaining the code.

 drivers/net/wireless/ath/ar5523/ar5523.c | 33 ++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/drivers/net/wireless/ath/ar5523/ar5523.c b/drivers/net/wireless/ath/ar5523/ar5523.c
index 6f937d2cc126..d7e86dc4c293 100644
--- a/drivers/net/wireless/ath/ar5523/ar5523.c
+++ b/drivers/net/wireless/ath/ar5523/ar5523.c
@@ -1581,8 +1581,41 @@ static int ar5523_probe(struct usb_interface *intf,
 	struct usb_device *dev = interface_to_usbdev(intf);
 	struct ieee80211_hw *hw;
 	struct ar5523 *ar;
+	struct usb_host_interface *host = intf->cur_altsetting;
 	int error = -ENOMEM;
 
+	if (host->desc.bNumEndpoints != 4) {
+		dev_err(&dev->dev, "Wrong number of endpoints\n");
+		return -ENODEV;
+	}
+
+	// Check for type of endpoint and direction.
+	for (int i = 0; i < host->desc.bNumEndpoints; ++i) {
+		struct usb_endpoint_descriptor *ep = &host->endpoint[i].desc;
+
+		switch (i) {
+		case 0:
+		case 1:
+			// if endpoint direction and type does not match
+			if (!((ep->bEndpointAddress & USB_DIR_OUT) &&
+			      ((ep->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK)
+			      == USB_ENDPOINT_XFER_BULK))){
+				dev_err(&dev->dev, "Wrong type of endpoints\n");
+				return -ENODEV;
+			}
+			break;
+		case 2:
+		case 3:
+			if (!((ep->bEndpointAddress & USB_DIR_IN) &&
+			      ((ep->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK)
+			     == USB_ENDPOINT_XFER_BULK))){
+				dev_err(&dev->dev, "Wrong type of endpoints\n");
+				return -ENODEV;
+			}
+			break;
+		}
+	}
+
 	/*
 	 * Load firmware if the device requires it.  This will return
 	 * -ENXIO on success and we'll get called back afer the usb
-- 
2.37.2