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From:   Pavel Skripkin <paskripkin@gmail.com>
To:     bernie@plugable.com, deller@gmx.de
Cc:     linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org,
        Pavel Skripkin <paskripkin@gmail.com>,
        syzbot+53ce4a4246d0fe0fee34@syzkaller.appspotmail.com
Subject: [PATCH] fbdev: udlfb: properly check endpoint type
Date:   Tue, 22 Mar 2022 23:04:38 +0300
Message-Id: <20220322200438.17998-1-paskripkin@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

syzbot reported warning in usb_submit_urb, which is caused by wrong
endpoint type.

This driver uses out bulk endpoint for communication, so
let's check if this endpoint is present and bail out early if not.

Fail log:

usb 1-1: BOGUS urb xfer, pipe 3 != type 1
WARNING: CPU: 0 PID: 4822 at drivers/usb/core/urb.c:493 usb_submit_urb+0xd27/0x1540 drivers/usb/core/urb.c:493
Modules linked in:
CPU: 0 PID: 4822 Comm: kworker/0:3 Tainted: G        W         5.13.0-syzkaller #0
...
Workqueue: usb_hub_wq hub_event
RIP: 0010:usb_submit_urb+0xd27/0x1540 drivers/usb/core/urb.c:493
...
Call Trace:
 dlfb_submit_urb+0x89/0x160 drivers/video/fbdev/udlfb.c:1969
 dlfb_set_video_mode+0x21f0/0x2950 drivers/video/fbdev/udlfb.c:315
 dlfb_ops_set_par+0x2a3/0x840 drivers/video/fbdev/udlfb.c:1110
 dlfb_usb_probe.cold+0x113e/0x1f4a drivers/video/fbdev/udlfb.c:1732
 usb_probe_interface+0x315/0x7f0 drivers/usb/core/driver.c:396

Fixes: 88e58b1a42f8 ("Staging: add udlfb driver")
Reported-and-tested-by: syzbot+53ce4a4246d0fe0fee34@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
---
 drivers/video/fbdev/udlfb.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/video/fbdev/udlfb.c b/drivers/video/fbdev/udlfb.c
index b9cdd02c1000..2343c7955747 100644
--- a/drivers/video/fbdev/udlfb.c
+++ b/drivers/video/fbdev/udlfb.c
@@ -1649,8 +1649,9 @@ static int dlfb_usb_probe(struct usb_interface *intf,
 	const struct device_attribute *attr;
 	struct dlfb_data *dlfb;
 	struct fb_info *info;
-	int retval = -ENOMEM;
+	int retval;
 	struct usb_device *usbdev = interface_to_usbdev(intf);
+	struct usb_endpoint_descriptor *out;
 
 	/* usb initialization */
 	dlfb = kzalloc(sizeof(*dlfb), GFP_KERNEL);
@@ -1664,6 +1665,12 @@ static int dlfb_usb_probe(struct usb_interface *intf,
 	dlfb->udev = usb_get_dev(usbdev);
 	usb_set_intfdata(intf, dlfb);
 
+	retval = usb_find_common_endpoints(intf->cur_altsetting, NULL, &out, NULL, NULL);
+	if (retval) {
+		dev_err(&intf->dev, "Device should have at lease 1 bulk endpoint!\n");
+		goto error;
+	}
+
 	dev_dbg(&intf->dev, "console enable=%d\n", console);
 	dev_dbg(&intf->dev, "fb_defio enable=%d\n", fb_defio);
 	dev_dbg(&intf->dev, "shadow enable=%d\n", shadow);
@@ -1673,6 +1680,7 @@ static int dlfb_usb_probe(struct usb_interface *intf,
 	if (!dlfb_parse_vendor_descriptor(dlfb, intf)) {
 		dev_err(&intf->dev,
 			"firmware not recognized, incompatible device?\n");
+		retval = -ENODEV;
 		goto error;
 	}
 
@@ -1686,8 +1694,10 @@ static int dlfb_usb_probe(struct usb_interface *intf,
 
 	/* allocates framebuffer driver structure, not framebuffer memory */
 	info = framebuffer_alloc(0, &dlfb->udev->dev);
-	if (!info)
+	if (!info) {
+		retval = -ENOMEM;
 		goto error;
+	}
 
 	dlfb->info = info;
 	info->par = dlfb;
-- 
2.35.1