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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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        Haojian Zhuang <haojian.zhuang@gmail.com>,
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        Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>,
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        Thierry Reding <thierry.reding@gmail.com>,
        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 v2 07/26] usb: gadget: udc: gr_udc: remove usage of list iterator past the loop body
Date:   Tue,  8 Mar 2022 18:17:59 +0100
Message-Id: <20220308171818.384491-8-jakobkoschel@gmail.com>
In-Reply-To: <20220308171818.384491-1-jakobkoschel@gmail.com>
References: <20220308171818.384491-1-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/gr_udc.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/gadget/udc/gr_udc.c b/drivers/usb/gadget/udc/gr_udc.c
index 4b35739d3695..22096f8505de 100644
--- a/drivers/usb/gadget/udc/gr_udc.c
+++ b/drivers/usb/gadget/udc/gr_udc.c
@@ -1690,7 +1690,7 @@ static int gr_queue_ext(struct usb_ep *_ep, struct usb_request *_req,
 /* Dequeue JUST ONE request */
 static int gr_dequeue(struct usb_ep *_ep, struct usb_request *_req)
 {
-	struct gr_request *req;
+	struct gr_request *req = NULL, *iter;
 	struct gr_ep *ep;
 	struct gr_udc *dev;
 	int ret = 0;
@@ -1710,11 +1710,13 @@ static int gr_dequeue(struct usb_ep *_ep, struct usb_request *_req)
 	spin_lock_irqsave(&dev->lock, flags);
 
 	/* Make sure it's actually queued on this endpoint */
-	list_for_each_entry(req, &ep->queue, queue) {
-		if (&req->req == _req)
-			break;
+	list_for_each_entry(iter, &ep->queue, queue) {
+		if (&iter->req != _req)
+			continue;
+		req = iter;
+		break;
 	}
-	if (&req->req != _req) {
+	if (!req) {
 		ret = -EINVAL;
 		goto out;
 	}
-- 
2.25.1