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Date: Sat, 13 Jan 2024 09:31:17 +0100
From: Niklas =?utf-8?Q?S=C3=B6derlund?= <niklas.soderlund@ragnatech.se>
To: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
Cc: "David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Sergey Shtylyov <s.shtylyov@omp.ru>,
	Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>,
	Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
	Wolfram Sang <wsa+renesas@sang-engineering.com>,
	Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= <u.kleine-koenig@pengutronix.de>,
	netdev@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] net: ravb: Fix dma_addr_t truncation in error case
Message-ID: <20240113083117.GI1643864@ragnatech.se>
References: <20240113042221.480650-1-nikita.yoush@cogentembedded.com>
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In-Reply-To: <20240113042221.480650-1-nikita.yoush@cogentembedded.com>

Hello Nikita,

Thanks for your patch.

On 2024-01-13 10:22:21 +0600, Nikita Yushchenko wrote:
> In ravb_start_xmit(), ravb driver uses u32 variable to store result of
> dma_map_single() call. Since ravb hardware has 32-bit address fields in
> descriptors, this works properly when mapping is successful - it is
> platform's job to provide mapping addresses that fit into hardware
> limitations.
> 
> However, in failure case dma_map_single() returns DMA_MAPPING_ERROR
> constant that is 64-bit when dma_addr_t is 64-bit. Storing this constant
> in u32 leads to truncation, and further call to dma_mapping_error()
> fails to notice the error.
> 
> Fix that by storing result of dma_map_single() in a dma_addr_t
> variable.
> 
> Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper")
> Signed-off-by: Nikita Yushchenko <nikita.yoush@cogentembedded.com>

Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>

> ---
>  drivers/net/ethernet/renesas/ravb_main.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
> index 8649b3e90edb..0e3731f50fc2 100644
> --- a/drivers/net/ethernet/renesas/ravb_main.c
> +++ b/drivers/net/ethernet/renesas/ravb_main.c
> @@ -1949,7 +1949,7 @@ static netdev_tx_t ravb_start_xmit(struct sk_buff *skb, struct net_device *ndev)
>  	struct ravb_tstamp_skb *ts_skb;
>  	struct ravb_tx_desc *desc;
>  	unsigned long flags;
> -	u32 dma_addr;
> +	dma_addr_t dma_addr;
>  	void *buffer;
>  	u32 entry;
>  	u32 len;
> -- 
> 2.39.2
> 
> 

-- 
Kind Regards,
Niklas Söderlund