linux-kernel - Re: [PATCH 2/2] drivers: staging: wilc1000: Call kfree only for error cases

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Date:	Sun, 4 Oct 2015 09:44:57 +0100
From:	Greg KH <gregkh@...uxfoundation.org>
To:	Chandra S Gorentla <csgorentla@...il.com>
Cc:	dan.carpenter@...cle.com, johnny.kim@...el.com,
	rachel.kim@...el.com, chris.park@...el.com,
	linux-wireless@...r.kernel.org, devel@...verdev.osuosl.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] drivers: staging: wilc1000: Call kfree only for
 error cases

On Sat, Oct 03, 2015 at 02:57:30PM +0530, Chandra S Gorentla wrote:
>  - kfree is being called for the members of the queue without
>    de-queuing them; they are just inserted within this function;
>    they are supposed to be de-queued and freed in a function
>    for receiving the queue items
>  - goto statements are removed
>  - After kfree correction, there is no need for target block
>    of goto statement; hence it is removed
> 
> Signed-off-by: Chandra S Gorentla <csgorentla@...il.com>
> ---
>  drivers/staging/wilc1000/wilc_msgqueue.c | 22 ++++++----------------
>  1 file changed, 6 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/staging/wilc1000/wilc_msgqueue.c b/drivers/staging/wilc1000/wilc_msgqueue.c
> index 284a3f5..eae90be 100644
> --- a/drivers/staging/wilc1000/wilc_msgqueue.c
> +++ b/drivers/staging/wilc1000/wilc_msgqueue.c
> @@ -56,32 +56,30 @@ int wilc_mq_destroy(WILC_MsgQueueHandle *pHandle)
>  int wilc_mq_send(WILC_MsgQueueHandle *pHandle,
>  			     const void *pvSendBuffer, u32 u32SendBufferSize)
>  {
> -	int result = 0;
>  	unsigned long flags;
>  	Message *pstrMessage = NULL;
>  
>  	if ((!pHandle) || (u32SendBufferSize == 0) || (!pvSendBuffer)) {
>  		PRINT_ER("pHandle or pvSendBuffer is null\n");
> -		result = -EFAULT;
> -		goto ERRORHANDLER;
> +		return -EFAULT;
>  	}
>  
>  	if (pHandle->bExiting) {
>  		PRINT_ER("pHandle fail\n");
> -		result = -EFAULT;
> -		goto ERRORHANDLER;
> +		return -EFAULT;
>  	}
>  
>  	/* construct a new message */
>  	pstrMessage = kmalloc(sizeof(Message), GFP_ATOMIC);
>  	if (!pstrMessage)
>  		return -ENOMEM;
> +
>  	pstrMessage->u32Length = u32SendBufferSize;
>  	pstrMessage->pstrNext = NULL;
>  	pstrMessage->pvBuffer = kmalloc(u32SendBufferSize, GFP_ATOMIC);
>  	if (!pstrMessage->pvBuffer) {
> -		result = -ENOMEM;
> -		goto ERRORHANDLER;
> +		kfree(pstrMessage);
> +		return -ENOMEM;
>  	}
>  	memcpy(pstrMessage->pvBuffer, pvSendBuffer, u32SendBufferSize);
>  
> @@ -102,15 +100,7 @@ int wilc_mq_send(WILC_MsgQueueHandle *pHandle,
>  	spin_unlock_irqrestore(&pHandle->strCriticalSection, flags);
>  
>  	up(&pHandle->hSem);
> -
> -ERRORHANDLER:
> -	/* error occured, free any allocations */
> -	if (pstrMessage) {
> -		kfree(pstrMessage->pvBuffer);
> -		kfree(pstrMessage);
> -	}
> -
> -	return result;
> +	return 0;

Aren't you now leaking memory as you aren't freeing pstrMessage and the
buffer on the "normal" return path?

thanks,

greg k-h
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