linux-kernel - [PATCH 11/26] usb: gadget: net2272: remove usage of list iterator past the loop body

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Message-Id: <20220306175034.3084609-12-jakobkoschel@gmail.com>
Date:   Sun,  6 Mar 2022 18:50:19 +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 11/26] usb: gadget: net2272: 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/net2272.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/gadget/udc/net2272.c b/drivers/usb/gadget/udc/net2272.c
index 7c38057dcb4a..08ce0831c5e0 100644
--- a/drivers/usb/gadget/udc/net2272.c
+++ b/drivers/usb/gadget/udc/net2272.c
@@ -926,7 +926,7 @@ static int
 net2272_dequeue(struct usb_ep *_ep, struct usb_request *_req)
 {
 	struct net2272_ep *ep;
-	struct net2272_request *req;
+	struct net2272_request *req = NULL, *tmp;
 	unsigned long flags;
 	int stopped;
 
@@ -939,11 +939,13 @@ net2272_dequeue(struct usb_ep *_ep, struct usb_request *_req)
 	ep->stopped = 1;
 
 	/* make sure it's still queued on this endpoint */
-	list_for_each_entry(req, &ep->queue, queue) {
-		if (&req->req == _req)
+	list_for_each_entry(tmp, &ep->queue, queue) {
+		if (&tmp->req == _req) {
+			req = tmp;
 			break;
+		}
 	}
-	if (&req->req != _req) {
+	if (!req) {
 		ep->stopped = stopped;
 		spin_unlock_irqrestore(&ep->dev->lock, flags);
 		return -EINVAL;
@@ -954,7 +956,6 @@ net2272_dequeue(struct usb_ep *_ep, struct usb_request *_req)
 		dev_dbg(ep->dev->dev, "unlink (%s) pio\n", _ep->name);
 		net2272_done(ep, req, -ECONNRESET);
 	}
-	req = NULL;
 	ep->stopped = stopped;
 
 	spin_unlock_irqrestore(&ep->dev->lock, flags);
-- 
2.25.1