linux-kernel - Re: [PATCH v6] staging: r8188eu: fix a potential memory leak in rtw_init_cmd

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Date:   Tue, 13 Sep 2022 21:14:32 +0200
From:   philipp hortmann <philipp.g.hortmann@...il.com>
To:     xkernel.wang@...mail.com
Cc:     Larry.Finger@...inger.net, phil@...lpotter.co.uk,
        gregkh@...uxfoundation.org, linux-staging@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6] staging: r8188eu: fix a potential memory leak in
 rtw_init_cmd_priv()

On Fri, Sep 09, 2022 at 07:45:57PM +0800, xkernel.wang@...mail.com wrote:
> From: Xiaoke Wang <xkernel.wang@...mail.com>
> 
> In rtw_init_cmd_priv(), if `pcmdpriv->rsp_allocated_buf` is allocated
> in failure, then `pcmdpriv->cmd_allocated_buf` will not be properly
> released. Besides, considering there are only two error paths and the
> first one can directly return, we do not need to implicitly jump to the
> `exit` tag to execute the error handling code.
> 
> So this patch added `kfree(pcmdpriv->cmd_allocated_buf);` on the error
> path to release the resource and simplified the return logic of
> rtw_init_cmd_priv(). As there is no proper device to test with, no
> runtime testing was performed.
> 
> Signed-off-by: Xiaoke Wang <xkernel.wang@...mail.com>
> ---
> ChangeLog:
> v1->v2: simplify the function.
> v2->v3: rebase and recover some whitespace cleanups.
> v3->v4: update the description.
> v4->v5: rebase...
> v5->v6: update the description.
>  drivers/staging/r8188eu/core/rtw_cmd.c | 15 +++++----------
>  1 file changed, 5 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/staging/r8188eu/core/rtw_cmd.c b/drivers/staging/r8188eu/core/rtw_cmd.c
> index 9c700ff..e38a826 100644
> --- a/drivers/staging/r8188eu/core/rtw_cmd.c
> +++ b/drivers/staging/r8188eu/core/rtw_cmd.c
> @@ -58,8 +58,6 @@ static int _rtw_enqueue_cmd(struct __queue *queue, struct cmd_obj *obj)
>  
>  u32	rtw_init_cmd_priv(struct cmd_priv *pcmdpriv)
>  {
> -	u32 res = _SUCCESS;
> -
>  	init_completion(&pcmdpriv->enqueue_cmd);
>  	/* sema_init(&(pcmdpriv->cmd_done_sema), 0); */
>  	init_completion(&pcmdpriv->start_cmd_thread);
> @@ -74,27 +72,24 @@ u32	rtw_init_cmd_priv(struct cmd_priv *pcmdpriv)
>  	pcmdpriv->cmd_allocated_buf = kzalloc(MAX_CMDSZ + CMDBUFF_ALIGN_SZ,
>  					      GFP_KERNEL);
>  
> -	if (!pcmdpriv->cmd_allocated_buf) {
> -		res = _FAIL;
> -		goto exit;
> -	}
> +	if (!pcmdpriv->cmd_allocated_buf)
> +		return _FAIL;
>  
>  	pcmdpriv->cmd_buf = pcmdpriv->cmd_allocated_buf  +  CMDBUFF_ALIGN_SZ - ((size_t)(pcmdpriv->cmd_allocated_buf) & (CMDBUFF_ALIGN_SZ - 1));
>  
>  	pcmdpriv->rsp_allocated_buf = kzalloc(MAX_RSPSZ + 4, GFP_KERNEL);
>  
>  	if (!pcmdpriv->rsp_allocated_buf) {
> -		res = _FAIL;
> -		goto exit;
> +		kfree(pcmdpriv->cmd_allocated_buf);
> +		return _FAIL;
>  	}
>  
>  	pcmdpriv->rsp_buf = pcmdpriv->rsp_allocated_buf  +  4 - ((size_t)(pcmdpriv->rsp_allocated_buf) & 3);
>  
>  	pcmdpriv->cmd_done_cnt = 0;
>  	pcmdpriv->rsp_cnt = 0;
> -exit:
>  
> -	return res;
> +	return _SUCCESS;
>  }
>  
>  u32 rtw_init_evt_priv(struct evt_priv *pevtpriv)
> --

Tested-by: Philipp Hortmann <philipp.g.hortmann@...il.com> # Edimax N150