[U-Boot] [PATCH v2 06/13] net: ravb: Fix signed shift overflow

[Marek Vasut]

On 08/27/2018 10:24 PM, Eugeniu Rosca wrote:
> Hi Marek,

Hi,

> On Mon, Aug 27, 2018 at 01:22:54AM +0200, Marek Vasut wrote:
>> On 08/27/2018 01:13 AM, Eugeniu Rosca wrote:
> [...]
>>>  
>>>  #define RAVB_DESC_DT(n)			((n) << 28)
>>
>> What about changing this instead, ((u32)(n) << 28) ?
> 
> This works too.
> 
> [...]
> 
>>>  
>>> -	writel((mac[0] << 24) | (mac[1] << 16) | (mac[2] << 8) | mac[3],
>>> -	       eth->iobase + RAVB_REG_MAHR);
>>> +	writel(((u32)mac[0] << 24) | ((u32)mac[1] << 16) | ((u32)mac[2] << 8) |
>>> +	       mac[3], eth->iobase + RAVB_REG_MAHR);
>>
>> Not a big fan of the casts here, I wonder if there isn't some more
>> elegant solution. If not, so be it.
> 
> Actually one cast is enough to fix the UB.
> Let me know if below patch looks better to you.

I guess, it's less intrusive. What do you think ?

> diff --git a/drivers/net/ravb.c b/drivers/net/ravb.c
> index 749562db960e..2190811c53bb 100644
> --- a/drivers/net/ravb.c
> +++ b/drivers/net/ravb.c
> @@ -72,7 +72,7 @@
>  #define RAVB_TX_QUEUE_OFFSET		0
>  #define RAVB_RX_QUEUE_OFFSET		4
>  
> -#define RAVB_DESC_DT(n)			((n) << 28)
> +#define RAVB_DESC_DT(n)			((u32)(n) << 28)
>  #define RAVB_DESC_DT_FSINGLE		RAVB_DESC_DT(0x7)
>  #define RAVB_DESC_DT_LINKFIX		RAVB_DESC_DT(0x9)
>  #define RAVB_DESC_DT_EOS		RAVB_DESC_DT(0xa)
> @@ -342,7 +342,7 @@ static int ravb_write_hwaddr(struct udevice *dev)
>  	struct eth_pdata *pdata = dev_get_platdata(dev);
>  	unsigned char *mac = pdata->enetaddr;
>  
> -	writel((mac[0] << 24) | (mac[1] << 16) | (mac[2] << 8) | mac[3],
> +	writel(((u32)mac[0] << 24) | (mac[1] << 16) | (mac[2] << 8) | mac[3],
>  	       eth->iobase + RAVB_REG_MAHR);
>  
>  	writel((mac[4] << 8) | mac[5], eth->iobase + RAVB_REG_MALR);
> 
> 
> Thanks,
> Eugeniu.
> 


-- 
Best regards,
Marek Vasut