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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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        Nicolas Ferre <nicolas.ferre@microchip.com>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Claudiu Beznea <claudiu.beznea@microchip.com>,
        Cristian Birsan <cristian.birsan@microchip.com>,
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        Vladimir Zapolskiy <vz@mleia.com>,
        Daniel Mack <daniel@zonque.org>,
        Haojian Zhuang <haojian.zhuang@gmail.com>,
        Robert Jarzmik <robert.jarzmik@free.fr>,
        Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>,
        Alim Akhtar <alim.akhtar@samsung.com>,
        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 16/26] usb: gadget: aspeed: remove usage of list iterator past the loop body
Date:   Tue,  8 Mar 2022 18:18:08 +0100
Message-Id: <20220308171818.384491-17-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/aspeed-vhub/epn.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/gadget/udc/aspeed-vhub/epn.c b/drivers/usb/gadget/udc/aspeed-vhub/epn.c
index 917892ca8753..b5252880b389 100644
--- a/drivers/usb/gadget/udc/aspeed-vhub/epn.c
+++ b/drivers/usb/gadget/udc/aspeed-vhub/epn.c
@@ -466,19 +466,21 @@ static int ast_vhub_epn_dequeue(struct usb_ep* u_ep, struct usb_request *u_req)
 {
 	struct ast_vhub_ep *ep = to_ast_ep(u_ep);
 	struct ast_vhub *vhub = ep->vhub;
-	struct ast_vhub_req *req;
+	struct ast_vhub_req *req = NULL, *iter;
 	unsigned long flags;
 	int rc = -EINVAL;
 
 	spin_lock_irqsave(&vhub->lock, flags);
 
 	/* Make sure it's actually queued on this endpoint */
-	list_for_each_entry (req, &ep->queue, queue) {
-		if (&req->req == u_req)
-			break;
+	list_for_each_entry(iter, &ep->queue, queue) {
+		if (&iter->req != u_req)
+			continue;
+		req = iter;
+		break;
 	}
 
-	if (&req->req == u_req) {
+	if (req) {
 		EPVDBG(ep, "dequeue req @%p active=%d\n",
 		       req, req->active);
 		if (req->active)
-- 
2.25.1