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From:   Jakob Koschel <jakobkoschel@gmail.com>
To:     Greg Kroah-Hartman <greg@kroah.com>
Cc:     Jakob Koschel <jakobkoschel@gmail.com>,
        linux-kernel@vger.kernel.org,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Felipe Balbi <balbi@kernel.org>, Joel Stanley <joel@jms.id.au>,
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        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Claudiu Beznea <claudiu.beznea@microchip.com>,
        Cristian Birsan <cristian.birsan@microchip.com>,
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        Robert Jarzmik <robert.jarzmik@free.fr>,
        Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>,
        Alim Akhtar <alim.akhtar@samsung.com>,
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        Jonathan Hunter <jonathanh@nvidia.com>,
        Michal Simek <michal.simek@xilinx.com>,
        linux-usb@vger.kernel.org (open list:USB GADGET/PERIPHERAL SUBSYSTEM),
        Mike Rapoport <rppt@kernel.org>,
        "Brian Johannesmeyer" <bjohannesmeyer@gmail.com>,
        Cristiano Giuffrida <c.giuffrida@vu.nl>,
        "Bos, H.J." <h.j.bos@vu.nl>
Subject: [PATCH 05/26] usb: gadget: udc: at91: remove usage of list iterator past the loop body
Date:   Sun,  6 Mar 2022 18:50:13 +0100
Message-Id: <20220306175034.3084609-6-jakobkoschel@gmail.com>
In-Reply-To: <20220306175034.3084609-1-jakobkoschel@gmail.com>
References: <20220306175034.3084609-1-jakobkoschel@gmail.com>
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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@gmail.com>
---
 drivers/usb/gadget/udc/at91_udc.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/gadget/udc/at91_udc.c b/drivers/usb/gadget/udc/at91_udc.c
index 9040a0561466..3578b061a3ee 100644
--- a/drivers/usb/gadget/udc/at91_udc.c
+++ b/drivers/usb/gadget/udc/at91_udc.c
@@ -704,7 +704,7 @@ static int at91_ep_queue(struct usb_ep *_ep,
 static int at91_ep_dequeue(struct usb_ep *_ep, struct usb_request *_req)
 {
 	struct at91_ep		*ep;
-	struct at91_request	*req;
+	struct at91_request	*req = NULL, *tmp;
 	unsigned long		flags;
 	struct at91_udc		*udc;
 
@@ -717,11 +717,13 @@ static int at91_ep_dequeue(struct usb_ep *_ep, struct usb_request *_req)
 	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->req == _req)
+	list_for_each_entry(tmp, &ep->queue, queue) {
+		if (&tmp->req == _req) {
+			req = tmp;
 			break;
+		}
 	}
-	if (&req->req != _req) {
+	if (!req) {
 		spin_unlock_irqrestore(&udc->lock, flags);
 		return -EINVAL;
 	}
-- 
2.25.1