linux-kernel - Re: [PATCH] net: ethernet: nixge: fix NULL dereference

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Date:   Fri, 25 Nov 2022 14:30:54 +0100
From:   Maciej Fijalkowski <maciej.fijalkowski@...el.com>
To:     Yuri Karpov <YKarpov@...ras.ru>
CC:     "David S . Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <lvc-project@...uxtesting.org>
Subject: Re: [PATCH] net: ethernet: nixge: fix NULL dereference

On Thu, Nov 24, 2022 at 11:43:03AM +0300, Yuri Karpov wrote:
> In function nixge_hw_dma_bd_release() dereference of NULL pointer
> priv->rx_bd_v is possible for the case of its allocation failure in
> nixge_hw_dma_bd_init().
> 
> Move for() loop with priv->rx_bd_v dereference under the check for
> its validity.
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Fixes: 492caffa8a1a ("net: ethernet: nixge: Add support for National Instruments XGE netdev")
> Signed-off-by: Yuri Karpov <YKarpov@...ras.ru>

Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@...el.com>

> ---
>  drivers/net/ethernet/ni/nixge.c | 29 +++++++++++++++--------------
>  1 file changed, 15 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/net/ethernet/ni/nixge.c b/drivers/net/ethernet/ni/nixge.c
> index 19d043b593cc..62320be4de5a 100644
> --- a/drivers/net/ethernet/ni/nixge.c
> +++ b/drivers/net/ethernet/ni/nixge.c
> @@ -249,25 +249,26 @@ static void nixge_hw_dma_bd_release(struct net_device *ndev)
>  	struct sk_buff *skb;
>  	int i;
>  
> -	for (i = 0; i < RX_BD_NUM; i++) {
> -		phys_addr = nixge_hw_dma_bd_get_addr(&priv->rx_bd_v[i],
> -						     phys);
> -
> -		dma_unmap_single(ndev->dev.parent, phys_addr,
> -				 NIXGE_MAX_JUMBO_FRAME_SIZE,
> -				 DMA_FROM_DEVICE);
> -
> -		skb = (struct sk_buff *)(uintptr_t)
> -			nixge_hw_dma_bd_get_addr(&priv->rx_bd_v[i],
> -						 sw_id_offset);
> -		dev_kfree_skb(skb);
> -	}
> +	if (priv->rx_bd_v) {
> +		for (i = 0; i < RX_BD_NUM; i++) {
> +			phys_addr = nixge_hw_dma_bd_get_addr(&priv->rx_bd_v[i],
> +							     phys);
> +
> +			dma_unmap_single(ndev->dev.parent, phys_addr,
> +					 NIXGE_MAX_JUMBO_FRAME_SIZE,
> +					 DMA_FROM_DEVICE);
> +
> +			skb = (struct sk_buff *)(uintptr_t)
> +				nixge_hw_dma_bd_get_addr(&priv->rx_bd_v[i],
> +							 sw_id_offset);
> +			dev_kfree_skb(skb);
> +		}
>  
> -	if (priv->rx_bd_v)
>  		dma_free_coherent(ndev->dev.parent,
>  				  sizeof(*priv->rx_bd_v) * RX_BD_NUM,
>  				  priv->rx_bd_v,
>  				  priv->rx_bd_p);
> +	}
>  
>  	if (priv->tx_skb)
>  		devm_kfree(ndev->dev.parent, priv->tx_skb);
> -- 
> 2.34.1
>