linux-kernel - [PATCH v2] usb: cdns3: change place of 'priv_ep' assignment in cdns3_gadget_ep_dequeue(), cdns3_gadget_ep

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Date:   Mon, 18 Jul 2022 19:00:52 +0300
From:   Andrey Strachuk <strochuk@...ras.ru>
To:     Peter Chen <peter.chen@...nel.org>
Cc:     Andrey Strachuk <strochuk@...ras.ru>,
        Pawel Laszczak <pawell@...ence.com>,
        Roger Quadros <rogerq@...nel.org>,
        Aswath Govindraju <a-govindraju@...com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        ldv-project@...uxtesting.org
Subject: [PATCH v2] usb: cdns3: change place of 'priv_ep' assignment in cdns3_gadget_ep_dequeue(), cdns3_gadget_ep_enable()

If 'ep' is NULL, result of ep_to_cdns3_ep(ep) is invalid pointer
and its dereference with priv_ep->cdns3_dev may cause panic.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Andrey Strachuk <strochuk@...ras.ru>
Fixes: 7733f6c32e36 ("usb: cdns3: Add Cadence USB3 DRD Driver")
---
 drivers/usb/cdns3/cdns3-gadget.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3-gadget.c
index 5c15c48952a6..aea5db0ec72d 100644
--- a/drivers/usb/cdns3/cdns3-gadget.c
+++ b/drivers/usb/cdns3/cdns3-gadget.c
@@ -2285,13 +2285,14 @@ static int cdns3_gadget_ep_enable(struct usb_ep *ep,
 	int val;

 	priv_ep = ep_to_cdns3_ep(ep);
-	priv_dev = priv_ep->cdns3_dev;
-	comp_desc = priv_ep->endpoint.comp_desc;
 
 	if (!ep || !desc || desc->bDescriptorType != USB_DT_ENDPOINT) {
 		dev_dbg(priv_dev->dev, "usbss: invalid parameters\n");
 		return -EINVAL;
 	}
+
+	comp_desc = priv_ep->endpoint.comp_desc;
+	priv_dev = priv_ep->cdns3_dev;

 	if (!desc->wMaxPacketSize) {
 		dev_err(priv_dev->dev, "usbss: missing wMaxPacketSize\n");
@@ -2600,7 +2601,7 @@ int cdns3_gadget_ep_dequeue(struct usb_ep *ep,
 			    struct usb_request *request)
 {
 	struct cdns3_endpoint *priv_ep = ep_to_cdns3_ep(ep);
-	struct cdns3_device *priv_dev = priv_ep->cdns3_dev;
+	struct cdns3_device *priv_dev;
 	struct usb_request *req, *req_temp;
 	struct cdns3_request *priv_req;
 	struct cdns3_trb *link_trb;
@@ -2610,6 +2611,8 @@ int cdns3_gadget_ep_dequeue(struct usb_ep *ep,
 
 	if (!ep || !request || !ep->desc)
 		return -EINVAL;
+
+	priv_dev = priv_ep->cdns3_dev;

 	spin_lock_irqsave(&priv_dev->lock, flags);

-- 
2.25.1