linux-kernel - [PATCH] usb: gadget: gadgetfs: correct dev state

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Message-Id: <1401973680-18413-1-git-send-email-marcus.nutzinger@theobroma-systems.com>
Date:	Thu,  5 Jun 2014 15:08:00 +0200
From:	Marcus Nutzinger <marcus.nutzinger@...obroma-systems.com>
To:	Felipe Balbi <balbi@...com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	Marcus Nutzinger <marcus.nutzinger@...obroma-systems.com>
Subject: [PATCH] usb: gadget: gadgetfs: correct dev state

Commit 1826e9b1 fixes the use after free of "dev".
However if this is not the final call to dev_release()
and the state is not reset to STATE_DEV_DISABLED and
hence all further open() calls to the gadgetfs ep0
device will fail with EBUSY.

So this commit reverts 1826e9b1 and places the call
put_dev() after setting the state.

Signed-off-by: Marcus Nutzinger <marcus.nutzinger@...obroma-systems.com>
Reviewed-by: Christoph Muellner <christoph.muellner@...obroma-systems.com>
---
 drivers/usb/gadget/inode.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/inode.c b/drivers/usb/gadget/inode.c
index a925d0c..6330528 100644
--- a/drivers/usb/gadget/inode.c
+++ b/drivers/usb/gadget/inode.c
@@ -1264,8 +1264,13 @@ dev_release (struct inode *inode, struct file *fd)
 
 	kfree (dev->buf);
 	dev->buf = NULL;
-	put_dev (dev);
 
+	/* other endpoints were all decoupled from this device */
+	spin_lock_irq(&dev->lock);
+	dev->state = STATE_DEV_DISABLED;
+	spin_unlock_irq(&dev->lock);
+
+	put_dev (dev);
 	return 0;
 }
 
-- 
1.9.0

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