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Message-ID: <53907C23.5060404@cogentembedded.com>
Date: Thu, 05 Jun 2014 18:18:11 +0400
From: Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To: Marcus Nutzinger <marcus.nutzinger@...obroma-systems.com>,
Felipe Balbi <balbi@...com>
CC: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: gadget: gadgetfs: correct dev state
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@...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);
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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