[PATCH v1] USB: sisusbvga: avoid initializing device in open

[PATCH v1] USB: sisusbvga: avoid initializing device in open

[Ayush]

The USB core holds minor_rwsem while invoking a USB character
device's open callback. sisusb_open() can currently initialize the
device while holding sisusb->lock, and that initialization performs
synchronous USB I/O.

High-speed devices are already initialized during probe. Treat a
probe-time initialization failure as a probe failure instead of
retrying initialization from open, so the open callback no longer
performs blocking device initialization.

Reported-by: syzbot+3bc656a9271e7c8a5c6b@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=3bc656a9271e7c8a5c6b
Signed-off-by: Ayush <ayush37735@gmail.com>
---
 drivers/usb/misc/sisusbvga/sisusbvga.c | 29 ++++++++++++--------------
 1 file changed, 13 insertions(+), 16 deletions(-)

diff --git a/drivers/usb/misc/sisusbvga/sisusbvga.c b/drivers/usb/misc/sisusbvga/sisusbvga.c
index 3e75a7c24828..6723a65b12b8 100644
--- a/drivers/usb/misc/sisusbvga/sisusbvga.c
+++ b/drivers/usb/misc/sisusbvga/sisusbvga.c
@@ -2223,20 +2223,10 @@ static int sisusb_open(struct inode *inode, struct file *file)
 	}
 
 	if (!sisusb->devinit) {
-		if (sisusb->sisusb_dev->speed == USB_SPEED_HIGH ||
-				sisusb->sisusb_dev->speed >= USB_SPEED_SUPER) {
-			if (sisusb_init_gfxdevice(sisusb, 0)) {
-				mutex_unlock(&sisusb->lock);
-				dev_err(&sisusb->sisusb_dev->dev,
-						"Failed to initialize device\n");
-				return -EIO;
-			}
-		} else {
-			mutex_unlock(&sisusb->lock);
-			dev_err(&sisusb->sisusb_dev->dev,
-					"Device not attached to USB 2.0 hub\n");
-			return -EIO;
-		}
+		mutex_unlock(&sisusb->lock);
+		dev_err(&sisusb->sisusb_dev->dev,
+			"Device not initialized\n");
+		return -EIO;
 	}
 
 	/* Increment usage count for our sisusb */
@@ -2880,9 +2870,16 @@ static int sisusb_probe(struct usb_interface *intf,
 
 	if (dev->speed == USB_SPEED_HIGH || dev->speed >= USB_SPEED_SUPER) {
 		int initscreen = 1;
-		if (sisusb_init_gfxdevice(sisusb, initscreen))
+
+		if (sisusb_init_gfxdevice(sisusb, initscreen)) {
 			dev_err(&sisusb->sisusb_dev->dev,
-					"Failed to early initialize device\n");
+				"Failed to early initialize device\n");
+			sisusb->present = 0;
+			usb_set_intfdata(intf, NULL);
+			usb_put_dev(sisusb->sisusb_dev);
+			retval = -EIO;
+			goto error_4;
+		}
 
 	} else
 		dev_info(&sisusb->sisusb_dev->dev,
-- 
2.53.0