linux-kernel - Re: [PATCH] staging: ks7010_sdio: fix NULL pointer dereference and memory leak

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Message-ID: <20180412150825.ckyvcmw2shvdbwvs@mwanda>
Date:   Thu, 12 Apr 2018 18:08:25 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        Colin King <colin.king@...onical.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: ks7010_sdio: fix NULL pointer dereference and
 memory leak

I added Colin to the Cc list.

On Thu, Apr 12, 2018 at 09:30:09AM -0500, Gustavo A. R. Silva wrote:
> priv is being dereferenced when it is still null, hence there is an
> explicit null pointer dereference at line 935: free_netdev(priv->net_dev)
> 
> Also, memory allocated for netdev at line 854:
> netdev = alloc_etherdev(sizeof(*priv));
> is not being free'd, hence there is a memory leak.
> 
> Fix this by null checking priv before dererefencing it and free netdev
> before return.
> 
> Addresses-Coverity-ID: 1467844 ("Explicit null dereferenced")
> Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
> ---
>  drivers/staging/ks7010/ks7010_sdio.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/staging/ks7010/ks7010_sdio.c b/drivers/staging/ks7010/ks7010_sdio.c
> index b8f55a1..f5d4c62 100644
> --- a/drivers/staging/ks7010/ks7010_sdio.c
> +++ b/drivers/staging/ks7010/ks7010_sdio.c
> @@ -932,8 +932,12 @@ static int ks7010_sdio_probe(struct sdio_func *func,
>  	return 0;
>  
>   err_free_netdev:
> -	free_netdev(priv->net_dev);
> -	card->priv = NULL;
> +	if (priv) {
> +		free_netdev(priv->net_dev);
> +		card->priv = NULL;

This isn't required because the next thing we do to card is kfree(card).

> +	} else {
> +		free_netdev(netdev);
> +	}


That's too complicated.  Just do:

err_free_netdev:
	free_netdev(net_dev);

err_release_irq:
	...

Please send a v2 patch.

regards,
dan carpenter