netdev - Re: [PATCH net-next] net: fddi: fix a possible null-ptr-deref

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Date:   Tue, 5 Jun 2018 21:08:14 +0800
From:   YueHaibing <yuehaibing@...wei.com>
To:     <davem@...emloft.net>
CC:     <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next] net: fddi: fix a possible null-ptr-deref

On 2018/6/5 18:06, YueHaibing wrote:
> bp->SharedMemAddr is set to NULL while bp->SharedMemSize less than 0,
> then memset will trigger null-ptr-deref.
> 
> Fix it use pci_zalloc_consistent when bp->SharedMemSize is greater than 0.
> 
> Signed-off-by: YueHaibing <yuehaibing@...wei.com>
> ---
>  drivers/net/fddi/skfp/skfddi.c | 10 ++++------
>  1 file changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/net/fddi/skfp/skfddi.c b/drivers/net/fddi/skfp/skfddi.c
> index 2414f1d..90164e0 100644
> --- a/drivers/net/fddi/skfp/skfddi.c
> +++ b/drivers/net/fddi/skfp/skfddi.c
> @@ -407,23 +407,21 @@ static  int skfp_driver_init(struct net_device *dev)
>  	if (bp->SharedMemSize > 0) {
>  		bp->SharedMemSize += 16;	// for descriptor alignment
>  
> -		bp->SharedMemAddr = pci_alloc_consistent(&bp->pdev,
> -							 bp->SharedMemSize,
> -							 &bp->SharedMemDMA);
> +		bp->SharedMemAddr = pci_zalloc_consistent(&bp->pdev,
> +							  bp->SharedMemSize,
> +							  &bp->SharedMemDMA);

This also need move from pci_dma* to dma_*, will send v2

>  		if (!bp->SharedMemAddr) {
>  			printk("could not allocate mem for ");
>  			printk("hardware module: %ld byte\n",
>  			       bp->SharedMemSize);
>  			goto fail;
>  		}
> -		bp->SharedMemHeap = 0;	// Nothing used yet.
>  
>  	} else {
>  		bp->SharedMemAddr = NULL;
> -		bp->SharedMemHeap = 0;
>  	}			// SharedMemSize > 0
>  
> -	memset(bp->SharedMemAddr, 0, bp->SharedMemSize);
> +	bp->SharedMemHeap = 0;
>  
>  	card_stop(smc);		// Reset adapter.
>  
>