Subject: Re: [patch -next] pch_can: off by one bugs

From: Wolfgang Grandegger <[email-masked]>
Date: Tue, 21 Dec 2010 21:41:52 +0100

Hello,

On 12/20/2010 10:26 AM, Dan Carpenter wrote:
> priv->tx_enable[] has PCH_TX_OBJ_END elements so this code is
> reading and writing one past the end of the array.
> 
> Signed-off-by: Dan Carpenter <[email-masked]>
> 
> diff --git a/drivers/net/can/pch_can.c b/drivers/net/can/pch_can.c
> index 8d45fdd..b2c1292 100644
> --- a/drivers/net/can/pch_can.c
> +++ b/drivers/net/can/pch_can.c
> @@ -1077,7 +1077,7 @@ static int pch_can_suspend(struct pci_dev *pdev, pm_message_t state)
>  	pch_can_set_int_enables(priv, PCH_CAN_DISABLE);
>  
>  	/* Save Tx buffer enable state */
> -	for (i = PCH_TX_OBJ_START; i <= PCH_TX_OBJ_END; i++)
> +	for (i = PCH_TX_OBJ_START; i < PCH_TX_OBJ_END; i++)
>  		priv->tx_enable[i] = pch_can_get_rxtx_ir(priv, i, PCH_TX_IFREG);
>  
>  	/* Disable all Transmit buffers */
> @@ -1138,7 +1138,7 @@ static int pch_can_resume(struct pci_dev *pdev)
>  	pch_can_set_optmode(priv);
>  
>  	/* Enabling the transmit buffer. */
> -	for (i = PCH_TX_OBJ_START; i <= PCH_TX_OBJ_END; i++)
> +	for (i = PCH_TX_OBJ_START; i < PCH_TX_OBJ_END; i++)
>  		pch_can_set_rxtx(priv, i, priv->tx_enable[i], PCH_TX_IFREG);
>  
>  	/* Configuring the receive buffer and enabling them. */
> 

This fix does not look correct too me. There are much more loop using
"i <= PCH_TX_OBJ_END" and the message numbering is from 1..32. Therefore
using "priv->tx_enable[i - 1]" seems more appropriate to me. Tomaya,
could you please check.

Thanks,

Wolfgang.