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Subject: Re: [PATCH] net: ravb: Fix dma_addr_t truncation in error case
To: Nikita Yushchenko <nikita.yoush@cogentembedded.com>, "David S. Miller"
	<davem@davemloft.net>, Jakub Kicinski <kuba@kernel.org>, Paolo Abeni
	<pabeni@redhat.com>
CC: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>, Yoshihiro Shimoda
	<yoshihiro.shimoda.uh@renesas.com>, Wolfram Sang
	<wsa+renesas@sang-engineering.com>, =?UTF-8?Q?Uwe_Kleine-K=c3=b6nig?=
	<u.kleine-koenig@pengutronix.de>, <netdev@vger.kernel.org>,
	<linux-renesas-soc@vger.kernel.org>, <linux-kernel@vger.kernel.org>
References: <20240113042221.480650-1-nikita.yoush@cogentembedded.com>
From: Sergey Shtylyov <s.shtylyov@omp.ru>
Organization: Open Mobile Platform
Message-ID: <bc89d250-0a08-e98c-588f-49c96e8e5474@omp.ru>
Date: Sat, 13 Jan 2024 12:43:03 +0300
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On 1/13/24 7:22 AM, 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: Sergey Shtylyov <s.shtylyov@omp.ru>

[...]

MBR, Sergey