Re: [PATCH] usb: gadget: gadgetfs: correct dev state

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Hello.

On 06/05/2014 05:08 PM, Marcus Nutzinger wrote:

Commit 1826e9b1 fixes the use after free of "dev".

   Please also specify that commit's summary line in parens.

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@xxxxxxxxxxxxxxxxxxxxx>
Reviewed-by: Christoph Muellner <christoph.muellner@xxxxxxxxxxxxxxxxxxxxx>
---
  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);

Not sure I understand why you need spinlock here... isn't the assignment atomic already?

+
+	put_dev (dev);
  	return 0;
  }

WBR, Sergei

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