Subject: Re: [PATCH] 3c515: Write outside array bounds

From: Roel Kluin <[email-masked]>
Date: Wed, 29 Jul 2009 16:13:24 +0200

Op 26-07-09 23:16, Jarek Poplawski schreef:
> Roel Kluin wrote, On 07/26/2009 12:35 AM:
> 
>> if dev_alloc_skb() fails on the first iteration, a write to
>> cp->rx_ring[-1] occurs.
>>
>> Signed-off-by: Roel Kluin <[email-masked]>
>> ---
>> Please review: can we error return like this?
> 
> 
> I doubt we can return here: there is a lot of cleaning missing.
> 
> Jarek P.
I took drivers/net/3c59x.c as an example

Is this going in the right direction?

diff --git a/drivers/net/3c515.c b/drivers/net/3c515.c
index 3e00fa8..e94867d 100644
--- a/drivers/net/3c515.c
+++ b/drivers/net/3c515.c
@@ -827,7 +827,7 @@ static int corkscrew_open(struct net_device *dev)
 			skb = dev_alloc_skb(PKT_BUF_SZ);
 			vp->rx_skbuff[i] = skb;
 			if (skb == NULL)
-				break;	/* Bad news!  */
+				goto error;	/* Bad news!  */
 			skb->dev = dev;	/* Mark as being used by this device. */
 			skb_reserve(skb, 2);	/* Align IP on 16 byte boundaries */
 			vp->rx_ring[i].addr = isa_virt_to_bus(skb->data);
@@ -864,6 +864,17 @@ static int corkscrew_open(struct net_device *dev)
 	     ioaddr + EL3_CMD);
 
 	return 0;
+error:
+	pr_emerg("%s: no memory for rx ring\n", dev->name);
+	int j;
+	for (j = 0; j < i; j++) {
+		if (vp->rx_skbuff[j]) {
+			dev_kfree_skb(vp->rx_skbuff[j]);
+			vp->rx_skbuff[j] = NULL;
+		}
+	}
+	free_irq(dev->irq, dev);
+	return -ENOMEM;
 }
 
 static void corkscrew_timer(unsigned long data)