linux-kernel - Re: [PATCH 1/2] net: ll_temac: fix DMA resources leak

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Date:   Mon, 30 Jan 2023 22:56:04 +0100
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Jonas Suhr Christensen <jsc@...raculum.org>, netdev@...r.kernel.org
Cc:     davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, michal.simek@...inx.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        esben@...nix.com
Subject: Re: [PATCH 1/2] net: ll_temac: fix DMA resources leak

Le 26/01/2023 à 11:16, Jonas Suhr Christensen a écrit :
> Add missing conversion of address when unmapping dma region causing
> unmapping to silently fail. At some point resulting in buffer
> overrun eg. when releasing device.
> 
> Signed-off-by: Jonas Suhr Christensen <jsc@...raculum.org>
> ---
>   drivers/net/ethernet/xilinx/ll_temac_main.c | 8 +++++++-
>   1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/xilinx/ll_temac_main.c b/drivers/net/ethernet/xilinx/ll_temac_main.c
> index 1066420d6a83..66c04027f230 100644
> --- a/drivers/net/ethernet/xilinx/ll_temac_main.c
> +++ b/drivers/net/ethernet/xilinx/ll_temac_main.c
> @@ -300,6 +300,7 @@ static void temac_dma_bd_release(struct net_device *ndev)
>   {
>   	struct temac_local *lp = netdev_priv(ndev);
>   	int i;
> +	struct cdmac_bd *bd;
>   
>   	/* Reset Local Link (DMA) */
>   	lp->dma_out(lp, DMA_CONTROL_REG, DMA_CONTROL_RST);
> @@ -307,9 +308,14 @@ static void temac_dma_bd_release(struct net_device *ndev)
>   	for (i = 0; i < lp->rx_bd_num; i++) {
>   		if (!lp->rx_skb[i])
>   			break;
> -		dma_unmap_single(ndev->dev.parent, lp->rx_bd_v[i].phys,
> +
> +		bd = &lp->rx_bd_v[1];

Hi,
just a naive question from s.o. who knows nothing of this code:

Is really [1] ([one]) expected here?
[i] would look more "standard" in a 'for' loop.

just my 2c,

CJ


> +		dma_unmap_single(ndev->dev.parent, be32_to_cpu(bd->phys),
>   				 XTE_MAX_JUMBO_FRAME_SIZE, DMA_FROM_DEVICE);
> +		bd->phys = 0;
> +		bd->len = 0;
>   		dev_kfree_skb(lp->rx_skb[i]);
> +		lp->rx_skb[i] = NULL;
>   	}
>   	if (lp->rx_bd_v)
>   		dma_free_coherent(ndev->dev.parent,