linux-kernel - [PATCH] usb:host: fix divide-by-zero in function fhci_queue

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Date:   Tue, 9 Apr 2019 22:37:12 +0800
From:   zhuyan <zhuyan34@...wei.com>
To:     <gregkh@...uxfoundation.org>, <anton@...msg.org>
CC:     <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <zhuyan34@...wei.com>
Subject: [PATCH] usb:host: fix divide-by-zero in function fhci_queue_urb

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: zhuyan <zhuyan34@...wei.com>
---
 drivers/usb/host/fhci-sched.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/host/fhci-sched.c b/drivers/usb/host/fhci-sched.c
index 3d12cdd..27ed63c 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);
@@ -765,11 +766,13 @@ void fhci_queue_urb(struct fhci_hcd *fhci, struct urb *urb)
 
 	switch (ed->mode) {
 	case FHCI_TF_BULK:
+		max_pkt_size = usb_maxpacket(urb->dev, urb->pipe,
+					usb_pipeout(urb->pipe));
 		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,
-- 
1.8.5.6