net/hamradio/6pack: Fix the size of a sk_buff used in 'sp_bump()'

We 'allocate' 'count' bytes here. In fact, 'dev_alloc_skb' already add some
extra space for padding, so a bit more is allocated.

However, we use 1 byte for the KISS command, then copy 'count' bytes, so
count+1 bytes.

Explicitly allocate and use 1 more byte to be safe.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/hamradio/6pack.c

@@ -344,10 +344,10 @@ static void sp_bump(struct sixpack *sp, char cmd)
 
 	sp->dev->stats.rx_bytes += count;
 
-	if ((skb = dev_alloc_skb(count)) == NULL)
+	if ((skb = dev_alloc_skb(count + 1)) == NULL)
 		goto out_mem;
 
-	ptr = skb_put(skb, count);
+	ptr = skb_put(skb, count + 1);
 	*ptr++ = cmd;	/* KISS command */
 
 	memcpy(ptr, sp->cooked_buf + 1, count);