linux-kernel - [PATCH 15/26] usb: gadget: udc-xilinx: remove usage of list iterator past the loop body

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Message-Id: <20220306175034.3084609-16-jakobkoschel@gmail.com>
Date:   Sun,  6 Mar 2022 18:50:23 +0100
From:   Jakob Koschel <jakobkoschel@...il.com>
To:     Greg Kroah-Hartman <greg@...ah.com>
Cc:     Jakob Koschel <jakobkoschel@...il.com>,
        linux-kernel@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Felipe Balbi <balbi@...nel.org>, Joel Stanley <joel@....id.au>,
        Andrew Jeffery <andrew@...id.au>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Claudiu Beznea <claudiu.beznea@...rochip.com>,
        Cristian Birsan <cristian.birsan@...rochip.com>,
        Al Cooper <alcooperx@...il.com>, Li Yang <leoyang.li@....com>,
        Vladimir Zapolskiy <vz@...ia.com>,
        Daniel Mack <daniel@...que.org>,
        Haojian Zhuang <haojian.zhuang@...il.com>,
        Robert Jarzmik <robert.jarzmik@...e.fr>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Michal Simek <michal.simek@...inx.com>,
        linux-usb@...r.kernel.org (open list:USB GADGET/PERIPHERAL SUBSYSTEM),
        Mike Rapoport <rppt@...nel.org>,
        "Brian Johannesmeyer" <bjohannesmeyer@...il.com>,
        Cristiano Giuffrida <c.giuffrida@...nl>,
        "Bos, H.J." <h.j.bos@...nl>
Subject: [PATCH 15/26] usb: gadget: udc-xilinx: remove usage of list iterator past the loop body

If the list representing the request queue does not contain the expected
request, the value of the list_for_each_entry() iterator will not point
to a valid structure. To avoid type confusion in such case, the list
iterator scope will be limited to the list_for_each_entry() loop.

In preparation to limiting scope of the list iterator to the list traversal
loop, use a dedicated pointer to point to the found request object [1].

Link: https://lore.kernel.org/all/YhdfEIwI4EdtHdym@kroah.com/
Signed-off-by: Jakob Koschel <jakobkoschel@...il.com>
---
 drivers/usb/gadget/udc/udc-xilinx.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/gadget/udc/udc-xilinx.c b/drivers/usb/gadget/udc/udc-xilinx.c
index 2907fad04e2c..34b7000f0602 100644
--- a/drivers/usb/gadget/udc/udc-xilinx.c
+++ b/drivers/usb/gadget/udc/udc-xilinx.c
@@ -1136,17 +1136,20 @@ static int xudc_ep_queue(struct usb_ep *_ep, struct usb_request *_req,
 static int xudc_ep_dequeue(struct usb_ep *_ep, struct usb_request *_req)
 {
 	struct xusb_ep *ep	= to_xusb_ep(_ep);
-	struct xusb_req *req	= to_xusb_req(_req);
+	struct xusb_req *req	= NULL;
+	struct xusb_req *tmp;
 	struct xusb_udc *udc	= ep->udc;
 	unsigned long flags;
 
 	spin_lock_irqsave(&udc->lock, flags);
 	/* Make sure it's actually queued on this endpoint */
-	list_for_each_entry(req, &ep->queue, queue) {
-		if (&req->usb_req == _req)
+	list_for_each_entry(tmp, &ep->queue, queue) {
+		if (&tmp->usb_req == _req) {
+			req = tmp;
 			break;
+		}
 	}
-	if (&req->usb_req != _req) {
+	if (!req) {
 		spin_unlock_irqrestore(&udc->lock, flags);
 		return -EINVAL;
 	}
-- 
2.25.1