USB: usbdevfs: sanitize flags more

Requesting a ZERO_PACKET or not is sensible only for output.
In the input direction the device decides.
Likewise accepting short packets makes sense only for input.

This allows operation with panic_on_warn without opening up
a local DOS.

Signed-off-by: Oliver Neukum <oneukum@suse.com>
Reported-by: syzbot+843efa30c8821bd69f53@syzkaller.appspotmail.com
Fixes: 0cb54a3 ("USB: debugging code shouldn't alter control flow")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/core/devio.c

@@ -1434,10 +1434,13 @@ static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb
 	struct async *as = NULL;
 	struct usb_ctrlrequest *dr = NULL;
 	unsigned int u, totlen, isofrmlen;
-	int i, ret, is_in, num_sgs = 0, ifnum = -1;
+	int i, ret, num_sgs = 0, ifnum = -1;
 	int number_of_packets = 0;
 	unsigned int stream_id = 0;
 	void *buf;
+	bool is_in;
+	bool allow_short = false;
+	bool allow_zero = false;
 	unsigned long mask =	USBDEVFS_URB_SHORT_NOT_OK |
 				USBDEVFS_URB_BULK_CONTINUATION |
 				USBDEVFS_URB_NO_FSBR |
@@ -1471,6 +1474,8 @@ static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb
 	u = 0;
 	switch (uurb->type) {
 	case USBDEVFS_URB_TYPE_CONTROL:
+		if (is_in)
+			allow_short = true;
 		if (!usb_endpoint_xfer_control(&ep->desc))
 			return -EINVAL;
 		/* min 8 byte setup packet */
@@ -1511,6 +1516,10 @@ static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb
 		break;
 
 	case USBDEVFS_URB_TYPE_BULK:
+		if (!is_in)
+			allow_zero = true;
+		else
+			allow_short = true;
 		switch (usb_endpoint_type(&ep->desc)) {
 		case USB_ENDPOINT_XFER_CONTROL:
 		case USB_ENDPOINT_XFER_ISOC:
@@ -1531,6 +1540,10 @@ static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb
 		if (!usb_endpoint_xfer_int(&ep->desc))
 			return -EINVAL;
  interrupt_urb:
+		if (!is_in)
+			allow_zero = true;
+		else
+			allow_short = true;
 		break;
 
 	case USBDEVFS_URB_TYPE_ISO:
@@ -1676,9 +1689,9 @@ static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb
 	u = (is_in ? URB_DIR_IN : URB_DIR_OUT);
 	if (uurb->flags & USBDEVFS_URB_ISO_ASAP)
 		u |= URB_ISO_ASAP;
-	if (uurb->flags & USBDEVFS_URB_SHORT_NOT_OK && is_in)
+	if (allow_short && uurb->flags & USBDEVFS_URB_SHORT_NOT_OK)
 		u |= URB_SHORT_NOT_OK;
-	if (uurb->flags & USBDEVFS_URB_ZERO_PACKET)
+	if (allow_zero && uurb->flags & USBDEVFS_URB_ZERO_PACKET)
 		u |= URB_ZERO_PACKET;
 	if (uurb->flags & USBDEVFS_URB_NO_INTERRUPT)
 		u |= URB_NO_INTERRUPT;