Subject: Re: [PATCH] net: off by one, try #2

From: Jarek Poplawski <[email-masked]>
Date: Wed, 11 Feb 2009 21:27:55 +0100

On Wed, Feb 11, 2009 at 08:33:25PM +0100, Roel Kluin wrote:
> Jarek Poplawski wrote:
> > On Wed, Feb 11, 2009 at 03:22:52PM +0100, Roel Kluin wrote:
> >>>> With while (x++ < n) { ... } x can reach n+1.
> >>> Yes, but it looks like here is even more...
> >>> i is also misused here and array can be overriden, so additional
> >>> break/return is needed.
> >> Thanks, is this how it should be?
> > 
> > It looks (almost) OK to me. :-) Except this > 80 line.
> > 
> > On the other hand, I wonder if it's not a good time to make it more
> > readable; I mean the first while (): length, ";", and maybe ++j
> > similarly to i now?
> > 
> > BTW, I hope you remember about irda.
> > 
> > Jarek P.
> 
> Thanks again for reviewing, how's this? with irda this time.

Hmm... except one bug: "stat & ..." needs "()"...

Roel, please resend once more, but separated: something could go to
stable, but not necessarily together. And add more description,
especially to this 3c505 (here is more changes than 'while (x++ < n)').

Anyway, I hope David will like these "off by one" patches again,
especially after this, and sun3lance one. Good catches!

Cheers,
Jarek P.

> -------------------->8----------------8<-----------------------
> 
> With while (x++ < n) { ... } x can reach n+1. As Jarek Poplawski pointed out, array
> pcb->data.raw was not correctly used.
> 
> Signed-off-by: Roel Kluin <[email-masked]>
> ---
> diff --git a/drivers/net/3c505.c b/drivers/net/3c505.c
> index 6124605..4ade64a 100644
> --- a/drivers/net/3c505.c
> +++ b/drivers/net/3c505.c
> @@ -493,15 +493,21 @@ static bool receive_pcb(struct net_device *dev, pcb_struct * pcb)
>  	}
>  	/* read the data */
>  	spin_lock_irqsave(&adapter->lock, flags);
> -	i = 0;
> -	do {
> -		j = 0;
> -		while (((stat = get_status(dev->base_addr)) & ACRF) == 0 && j++ < 20000);
> -		pcb->data.raw[i++] = inb_command(dev->base_addr);
> -		if (i > MAX_PCB_DATA)
> -			INVALID_PCB_MSG(i);
> -	} while ((stat & ASF_PCB_MASK) != ASF_PCB_END && j < 20000);
> +	for (i = 0; i < MAX_PCB_DATA; i++) {
> +		for (j = 0; j < 20000; j++) {
> +			stat = get_status(dev->base_addr);
> +			if (stat & ACRF)
> +				break;
> +		}
> +		pcb->data.raw[i] = inb_command(dev->base_addr);
> +		if (stat & ASF_PCB_MASK == ASF_PCB_END || j >= 20000)
> +			break;
> +	}
>  	spin_unlock_irqrestore(&adapter->lock, flags);
> +	if (i >= MAX_PCB_DATA) {
> +		INVALID_PCB_MSG(i);
> +		return false;
> +	}
>  	if (j >= 20000) {
>  		TIMEOUT_MSG(__LINE__);
>  		return false;
> diff --git a/drivers/net/irda/mcs7780.c b/drivers/net/irda/mcs7780.c
> index 7eafdca..85e88da 100644
> --- a/drivers/net/irda/mcs7780.c
> +++ b/drivers/net/irda/mcs7780.c
> @@ -585,7 +585,7 @@ static int mcs_speed_change(struct mcs_cb *mcs)
>  		mcs_get_reg(mcs, MCS_RESV_REG, &rval);
>  	} while(cnt++ < 100 && (rval & MCS_IRINTX));
>  
> -	if(cnt >= 100) {
> +	if (cnt > 100) {
>  		IRDA_ERROR("unable to change speed\n");
>  		ret = -EIO;
>  		goto error;
>