netdev - Re: [SCSI] cxgb3i: convert cdev->l2opt to use rcu to prevent NULL dereference (v2)

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Date:	Mon, 26 Sep 2011 10:20:52 -0400
From:	Neil Horman <nhorman@...driver.com>
To:	Dan Carpenter <dan.carpenter@...cle.com>
Cc:	netdev@...r.kernel.org, linux-scsi@...r.kernel.org
Subject: Re: [SCSI] cxgb3i: convert cdev->l2opt to use rcu to prevent NULL
 dereference (v2)

On Mon, Sep 26, 2011 at 04:40:48PM +0300, Dan Carpenter wrote:
> Hi Neil,
> 
> c98bc57ee65b6 "[SCSI] cxgb3i: convert cdev->l2opt to use rcu to
> prevent NULL dereference (v2)" from linux-next introduces a usinging
> uninitialized variable bug.
> 
>  struct l2t_entry *t3_l2t_get(struct t3cdev *cdev, struct neighbour *neigh,
>                              struct net_device *dev)
>  {
> -       struct l2t_entry *e;
> -       struct l2t_data *d = L2DATA(cdev);
> +       struct l2t_entry *e = NULL;
> +       struct l2t_data *d;
>         u32 addr = *(u32 *) neigh->primary_key;
>         int ifidx = neigh->dev->ifindex;
>         int hash = arp_hash(addr, ifidx, d);
>                                          ^
> Uninitialized variable.
> 
>         struct port_info *p = netdev_priv(dev);
>         int smt_idx = p->port_id;
>  
> +       rcu_read_lock();
> +       d = L2DATA(cdev);
> +       if (!d)
> +               goto done_rcu;
> +
> 
> regards,
> dan carpenter
> 

Yup, thanks, you need this to9 fix the uninitalized var.

Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Neil Horman <nhorman@...driver.com>

 l2t.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)


diff --git a/drivers/net/cxgb3/l2t.c b/drivers/net/cxgb3/l2t.c
index 3808f99..4154097 100644
--- a/drivers/net/cxgb3/l2t.c
+++ b/drivers/net/cxgb3/l2t.c
@@ -302,9 +302,9 @@ struct l2t_entry *t3_l2t_get(struct t3cdev *cdev, struct neighbour *neigh,
 {
 	struct l2t_entry *e = NULL;
 	struct l2t_data *d;
+	int hash;
 	u32 addr = *(u32 *) neigh->primary_key;
 	int ifidx = neigh->dev->ifindex;
-	int hash = arp_hash(addr, ifidx, d);
 	struct port_info *p = netdev_priv(dev);
 	int smt_idx = p->port_id;
 
@@ -313,6 +313,8 @@ struct l2t_entry *t3_l2t_get(struct t3cdev *cdev, struct neighbour *neigh,
 	if (!d)
 		goto done_rcu;
 
+	hash = arp_hash(addr, ifidx, d);
+
 	write_lock_bh(&d->lock);
 	for (e = d->l2tab[hash].first; e; e = e->next)
 		if (e->addr == addr && e->ifindex == ifidx &&

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