linux-kernel - Re: [PATCH 12/12] staging: r8188eu: check the return of kzalloc()

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Date:   Tue, 03 May 2022 00:08:46 -0700
From:   Joe Perches <joe@...ches.com>
To:     xkernel.wang@...mail.com, Larry.Finger@...inger.net,
        phil@...lpotter.co.uk, gregkh@...uxfoundation.org
Cc:     linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 12/12] staging: r8188eu: check the return of kzalloc()

On Tue, 2022-05-03 at 15:02 +0800, xkernel.wang@...mail.com wrote:
> From: Xiaoke Wang <xkernel.wang@...mail.com>
> 
> kzalloc() is a memory allocation function which can return NULL when
> some internal memory errors happen. So it is better to handle the return
> of it to prevent potential wrong memory access.
> 
> Besides, to propagate the error to the caller, the type of
> rtw_alloc_hwxmits() is changed to `int` and another check is added to
> its caller.
> Then if kzalloc() fails, the caller will properly jump to the
> corresponding error hanlding code.

It'd be better to use the typical error returns

> diff --git a/drivers/staging/r8188eu/core/rtw_xmit.c b/drivers/staging/r8188eu/core/rtw_xmit.c
[]
> @@ -176,7 +176,9 @@ s32	_rtw_init_xmit_priv(struct xmit_priv *pxmitpriv, struct adapter *padapter)
>  
>  	pxmitpriv->free_xmit_extbuf_cnt = num_xmit_extbuf;
>  
> -	rtw_alloc_hwxmits(padapter);
> +	res = rtw_alloc_hwxmits(padapter);
> +	if (res == _FAIL)
> +		goto free_xmit_extbuf;

	if (res)
		goto free_xmit_extbuf;

[]

> -void rtw_alloc_hwxmits(struct adapter *padapter)
> +int rtw_alloc_hwxmits(struct adapter *padapter)
>  {
>  	struct hw_xmit *hwxmits;
>  	struct xmit_priv *pxmitpriv = &padapter->xmitpriv;
> @@ -1495,6 +1497,8 @@ void rtw_alloc_hwxmits(struct adapter *padapter)
>  	pxmitpriv->hwxmit_entry = HWXMIT_ENTRY;
>  
>  	pxmitpriv->hwxmits = kzalloc(sizeof(struct hw_xmit) * pxmitpriv->hwxmit_entry, GFP_KERNEL);
> +	if (!pxmitpriv->hwxmits)

		return -ENOMEM;