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From: Simon Horman <horms@kernel.org>
To: Daniel Golle <daniel@makrotopia.org>
Cc: Dan Carpenter <dan.carpenter@linaro.org>,
	Felix Fietkau <nbd@nbd.name>, John Crispin <john@phrozen.org>,
	Sean Wang <sean.wang@mediatek.com>,
	Mark Lee <Mark-MC.Lee@mediatek.com>,
	Lorenzo Bianconi <lorenzo@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	AngeloGioacchino Del Regno
	<angelogioacchino.delregno@collabora.com>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org
Subject: Re: [PATCH net] net: ethernet: mtk_eth_soc: fix uninitialized variable
Date: Thu, 7 Sep 2023 18:21:31 +0200	[thread overview]
Message-ID: <20230907162131.GK434333@kernel.org> (raw)
In-Reply-To: <51d1ae238aecde07b2b4fe02cdab0dc87287cd96.1694099183.git.daniel@makrotopia.org>

On Thu, Sep 07, 2023 at 04:14:20PM +0100, Daniel Golle wrote:
> Variable dma_addr in function mtk_poll_rx can be uninitialized on
> some of the error paths. In practise this doesn't matter, even random
> data present in uninitialized stack memory can safely be used in the
> way it happens in the error path.
> 
> However, in order to make Smatch happy make sure the variable is
> always initialized.
> 
> Signed-off-by: Daniel Golle <daniel@makrotopia.org>
> ---
>  drivers/net/ethernet/mediatek/mtk_eth_soc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> index 31090490d47ce..6342eac90793e 100644
> --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> @@ -2119,11 +2119,11 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget,
>  	u8 *data, *new_data;
>  	struct mtk_rx_dma_v2 *rxd, trxd;
>  	int done = 0, bytes = 0;
> +	dma_addr_t dma_addr = NULL;

Hi Daniel,

I'm not sure that NULL is a valid value for a variable of type dma_addr_t.
Is DMA_MAPPING_ERROR more appropriate here?

Flagged by Sparse and, W=1 builds with gcc-13 and clang-16.

>  
>  	while (done < budget) {
>  		unsigned int pktlen, *rxdcsum;
>  		struct net_device *netdev;
> -		dma_addr_t dma_addr;
>  		u32 hash, reason;
>  		int mac = 0;
>  
> -- 
> 2.42.0
> 


WARNING: multiple messages have this Message-ID (diff)
From: Simon Horman <horms@kernel.org>
To: Daniel Golle <daniel@makrotopia.org>
Cc: Dan Carpenter <dan.carpenter@linaro.org>,
	Felix Fietkau <nbd@nbd.name>, John Crispin <john@phrozen.org>,
	Sean Wang <sean.wang@mediatek.com>,
	Mark Lee <Mark-MC.Lee@mediatek.com>,
	Lorenzo Bianconi <lorenzo@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	AngeloGioacchino Del Regno
	<angelogioacchino.delregno@collabora.com>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org
Subject: Re: [PATCH net] net: ethernet: mtk_eth_soc: fix uninitialized variable
Date: Thu, 7 Sep 2023 18:21:31 +0200	[thread overview]
Message-ID: <20230907162131.GK434333@kernel.org> (raw)
In-Reply-To: <51d1ae238aecde07b2b4fe02cdab0dc87287cd96.1694099183.git.daniel@makrotopia.org>

On Thu, Sep 07, 2023 at 04:14:20PM +0100, Daniel Golle wrote:
> Variable dma_addr in function mtk_poll_rx can be uninitialized on
> some of the error paths. In practise this doesn't matter, even random
> data present in uninitialized stack memory can safely be used in the
> way it happens in the error path.
> 
> However, in order to make Smatch happy make sure the variable is
> always initialized.
> 
> Signed-off-by: Daniel Golle <daniel@makrotopia.org>
> ---
>  drivers/net/ethernet/mediatek/mtk_eth_soc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> index 31090490d47ce..6342eac90793e 100644
> --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> @@ -2119,11 +2119,11 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget,
>  	u8 *data, *new_data;
>  	struct mtk_rx_dma_v2 *rxd, trxd;
>  	int done = 0, bytes = 0;
> +	dma_addr_t dma_addr = NULL;

Hi Daniel,

I'm not sure that NULL is a valid value for a variable of type dma_addr_t.
Is DMA_MAPPING_ERROR more appropriate here?

Flagged by Sparse and, W=1 builds with gcc-13 and clang-16.

>  
>  	while (done < budget) {
>  		unsigned int pktlen, *rxdcsum;
>  		struct net_device *netdev;
> -		dma_addr_t dma_addr;
>  		u32 hash, reason;
>  		int mac = 0;
>  
> -- 
> 2.42.0
> 

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2023-09-07 16:21 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-06 11:51 [bug report] net: ethernet: mtk_eth_soc: support 36-bit DMA addressing on MT7988 Dan Carpenter
2023-09-07 15:14 ` [PATCH net] net: ethernet: mtk_eth_soc: fix uninitialized variable Daniel Golle
2023-09-07 15:14   ` Daniel Golle
2023-09-07 16:21   ` Simon Horman [this message]
2023-09-07 16:21     ` Simon Horman
2023-09-07 16:53   ` kernel test robot
2023-09-07 16:53     ` kernel test robot
2023-09-07 17:14   ` kernel test robot
2023-09-07 17:14     ` kernel test robot
2023-09-08  6:58   ` Dan Carpenter
2023-09-08  6:58     ` Dan Carpenter
2023-09-10 21:40 ` [PATCH net v2] " Daniel Golle
2023-09-10 21:40   ` Daniel Golle
2023-09-11  9:40   ` patchwork-bot+netdevbpf
2023-09-11  9:40     ` patchwork-bot+netdevbpf

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