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 <redacted>
Signed-off-by: Neil Horman <nhorman@tuxdriver.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 &&