linux-kernel - Re: [PATCH] net: ll_temac: check the return value of devm

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Date:   Thu, 17 Feb 2022 08:52:02 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     xkernel.wang@...mail.com
Cc:     davem@...emloft.net, michal.simek@...inx.com,
        netdev@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: ll_temac: check the return value of devm_kmalloc()

On Wed, 16 Feb 2022 18:46:42 +0800 xkernel.wang@...mail.com wrote:
> From: Xiaoke Wang <xkernel.wang@...mail.com>
> 
> devm_kmalloc() returns a pointer to allocated memory on success, NULL
> on failure. While lp->indirect_lock is allocated by devm_kmalloc()
> without proper check. It is better to check the value of it to
> prevent potential wrong memory access.
> 

Consider adding a Fixes tag, although I guess this is not a real bug
since tiny allocations don't really fail.

> Signed-off-by: Xiaoke Wang <xkernel.wang@...mail.com>
> ---
>  drivers/net/ethernet/xilinx/ll_temac_main.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/net/ethernet/xilinx/ll_temac_main.c b/drivers/net/ethernet/xilinx/ll_temac_main.c
> index 463094c..7c5dd39 100644
> --- a/drivers/net/ethernet/xilinx/ll_temac_main.c
> +++ b/drivers/net/ethernet/xilinx/ll_temac_main.c
> @@ -1427,6 +1427,11 @@ static int temac_probe(struct platform_device *pdev)
>  		lp->indirect_lock = devm_kmalloc(&pdev->dev,
>  						 sizeof(*lp->indirect_lock),
>  						 GFP_KERNEL);
> +		if (!lp->indirect_lock) {
> +			dev_err(&pdev->dev,
> +				"indirect register lock allocation failed\n");

There's no need for this message, kmalloc() will display an error
already.

> +			return -ENOMEM;
> +		}
>  		spin_lock_init(lp->indirect_lock);
>  	}
>