[PATCH] usb: host: fix divide-by-zero in function fhci_queue_urb

[Yan Zhu]

fhci_queue_urb() shouldn't use urb->pipe to compute the maxpacket
size anyway.It should use usb_endpoint_maxp(&urb->ep->desc).

In function fhci_queue_urb, the divisor of expression
(urb->transfer_buffer_length % usb_maxpacket(urb->dev, urb->pipe,
usb_pipeout(urb->pipe))) may be zero. When it is zero, unexpected results
may occur, so it is necessary to ensure that the divisor is not zero.

Signed-off-by: Yan Zhu <zhuyan34@xxxxxxxxxx>
---
 drivers/usb/host/fhci-sched.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/host/fhci-sched.c b/drivers/usb/host/fhci-sched.c
index 3d12cdd..7dcfe22 100644
--- a/drivers/usb/host/fhci-sched.c
+++ b/drivers/usb/host/fhci-sched.c
@@ -704,6 +704,7 @@ void fhci_queue_urb(struct fhci_hcd *fhci, struct urb *urb)
 	struct td *td;
 	u8 *data;
 	u16 cnt = 0;
+	u16 max_pkt_size = 0;
 
 	if (ed == NULL) {
 		ed = fhci_get_empty_ed(fhci);
@@ -727,8 +728,7 @@ void fhci_queue_urb(struct fhci_hcd *fhci, struct urb *urb)
 		}
 		ed->speed = (urb->dev->speed == USB_SPEED_LOW) ?
 			FHCI_LOW_SPEED : FHCI_FULL_SPEED;
-		ed->max_pkt_size = usb_maxpacket(urb->dev,
-			urb->pipe, usb_pipeout(urb->pipe));
+		ed->max_pkt_size = usb_endpoint_maxp(&urb->ep->desc);
 		urb->ep->hcpriv = ed;
 		fhci_dbg(fhci, "new ep speed=%d max_pkt_size=%d\n",
 			 ed->speed, ed->max_pkt_size);
@@ -765,11 +765,12 @@ void fhci_queue_urb(struct fhci_hcd *fhci, struct urb *urb)
 
 	switch (ed->mode) {
 	case FHCI_TF_BULK:
+		max_pkt_size = usb_endpoint_maxp(&urb->ep->desc);
 		if (urb->transfer_flags & URB_ZERO_PACKET &&
 				urb->transfer_buffer_length > 0 &&
+				(max_pkt_size != 0) &&
 				((urb->transfer_buffer_length %
-				usb_maxpacket(urb->dev, urb->pipe,
-				usb_pipeout(urb->pipe))) == 0))
+				max_pkt_size) == 0))
 			urb_state = US_BULK0;
 		while (data_len > 4096) {
 			td = fhci_td_fill(fhci, urb, urb_priv, ed, cnt,
@@ -807,8 +808,8 @@ void fhci_queue_urb(struct fhci_hcd *fhci, struct urb *urb)
 		break;
 	case FHCI_TF_CTRL:
 		ed->dev_addr = usb_pipedevice(urb->pipe);
-		ed->max_pkt_size = usb_maxpacket(urb->dev, urb->pipe,
-			usb_pipeout(urb->pipe));
+		ed->max_pkt_size = usb_endpoint_maxp(&urb->ep->desc);
+
 		/* setup stage */
 		td = fhci_td_fill(fhci, urb, urb_priv, ed, cnt++, FHCI_TA_SETUP,
 			USB_TD_TOGGLE_DATA0, urb->setup_packet, 8, 0, 0, true);
-- 
1.8.5.6