linux-kernel - Re: [PATCH v2] nfc: virtual_ncidev: Add variable to check if ndev is running

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Date:   Tue, 21 Nov 2023 17:17:03 +0900
From:   Bongsu Jeon <bongsu.jeon@...sung.com>
To:     Nguyen Dinh Phi <phind.uet@...il.com>,
        Bongsu Jeon <bongsu.jeon@...sung.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
CC:     "syzbot+6eb09d75211863f15e3e@...kaller.appspotmail.com" 
        <syzbot+6eb09d75211863f15e3e@...kaller.appspotmail.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] nfc: virtual_ncidev: Add variable to check if ndev
 is running

On 21/11/2023 16:54, Nguyen Dinh Phi wrote:
> syzbot reported an memory leak that happens when an skb is add to
> send_buff after virtual nci closed.
> This patch adds a variable to track if the ndev is running before
> handling new skb in send function.
> 
> Signed-off-by: Nguyen Dinh Phi <phind.uet@...il.com>
> Reported-by: syzbot+6eb09d75211863f15e3e@...kaller.appspotmail.com
> Closes: https://lore.kernel.org/lkml/00000000000075472b06007df4fb@google.com
> ---
> V2:
>     - Remove unused macro.
>     - Re-adding a line that was removed wrongly.
>  drivers/nfc/virtual_ncidev.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/nfc/virtual_ncidev.c b/drivers/nfc/virtual_ncidev.c
> index b027be0b0b6f..590b038e449e 100644
> --- a/drivers/nfc/virtual_ncidev.c
> +++ b/drivers/nfc/virtual_ncidev.c
> @@ -26,10 +26,14 @@ struct virtual_nci_dev {
>  	struct mutex mtx;
>  	struct sk_buff *send_buff;
>  	struct wait_queue_head wq;
> +	bool running;
>  };
>  
>  static int virtual_nci_open(struct nci_dev *ndev)
>  {
> +	struct virtual_nci_dev *vdev = nci_get_drvdata(ndev);
> +
> +	vdev->running = true;
>  	return 0;
>  }
>  
> @@ -40,6 +44,7 @@ static int virtual_nci_close(struct nci_dev *ndev)
>  	mutex_lock(&vdev->mtx);
>  	kfree_skb(vdev->send_buff);
>  	vdev->send_buff = NULL;
> +	vdev->running = false;
>  	mutex_unlock(&vdev->mtx);
>  
>  	return 0;
> @@ -50,7 +55,7 @@ static int virtual_nci_send(struct nci_dev *ndev, struct sk_buff *skb)
>  	struct virtual_nci_dev *vdev = nci_get_drvdata(ndev);
>  
>  	mutex_lock(&vdev->mtx);
> -	if (vdev->send_buff) {
> +	if (vdev->send_buff || !vdev->running) {
>  		mutex_unlock(&vdev->mtx);
>  		kfree_skb(skb);
>  		return -1;
> -- 
> 2.39.2


Reviewed-by: Bongsu Jeon

Best regards,
Bongsu