linux-kernel - [PATCH] usb: dwc3: gadget: Fix desc NULL pointer in dwc3_gadget_ep

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Message-ID: <20140903062634.GA27870@intel.com>
Date:	Wed, 3 Sep 2014 14:26:34 +0800
From:	Zhuang Jin Can <jin.can.zhuang@...el.com>
To:	balbi@...com
Cc:	david.a.cohen@...el.com, jiebing.li@...el.com, hang.yuan@...el.com,
	hao.wu@...el.com, gregkh@...uxfoundation.org,
	linux-usb@...r.kernel.org, linux-omap@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] usb: dwc3: gadget: Fix desc NULL pointer in
 dwc3_gadget_ep_queue()

dep->endpoint.desc is checked at the beginning of
dwc3_gadget_ep_queue(), but after that it may be set to NULL
by another thread and then accessed again in dwc3_gadget_ep_queue().
This will lead to kernel oops.

Expand spinlock protection area to aviod race condition.

Signed-off-by: Zhuang Jin Can <jin.can.zhuang@...el.com>
Signed-off-by: Jiebing Li <jiebing.li@...el.com>
---
 drivers/usb/dwc3/gadget.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 349cacc..e8fb231 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1225,16 +1225,17 @@ static int dwc3_gadget_ep_queue(struct usb_ep *ep, struct usb_request *request,
 
 	int				ret;
 
+	spin_lock_irqsave(&dwc->lock, flags);
 	if (!dep->endpoint.desc) {
 		dev_dbg(dwc->dev, "trying to queue request %p to disabled %s\n",
 				request, ep->name);
+		spin_unlock_irqrestore(&dwc->lock, flags);
 		return -ESHUTDOWN;
 	}
 
 	dev_vdbg(dwc->dev, "queing request %p to %s length %d\n",
 			request, ep->name, request->length);
 
-	spin_lock_irqsave(&dwc->lock, flags);
 	ret = __dwc3_gadget_ep_queue(dep, req);
 	spin_unlock_irqrestore(&dwc->lock, flags);
 
-- 
1.7.9.5

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