cxgb3i: convert cdev->l2opt to use rcu to prevent NULL dereference
commit e48f129c2f200dde8899f6ea5c6e7173674fc482 upstream.
This oops was reported recently:
d:mon> e
cpu 0xd: Vector: 300 (Data Access) at [c0000000fd4c7120]
pc: d00000000076f194: .t3_l2t_get+0x44/0x524 [cxgb3]
lr: d000000000b02108: .init_act_open+0x150/0x3d4 [cxgb3i]
sp: c0000000fd4c73a0
msr: 8000000000009032
dar: 0
dsisr: 40000000
current = 0xc0000000fd640d40
paca = 0xc00000000054ff80
pid = 5085, comm = iscsid
d:mon> t
[c0000000fd4c7450] d000000000b02108 .init_act_open+0x150/0x3d4 [cxgb3i]
[c0000000fd4c7500] d000000000e45378 .cxgbi_ep_connect+0x784/0x8e8 [libcxgbi]
[c0000000fd4c7650] d000000000db33f0 .iscsi_if_rx+0x71c/0xb18
[scsi_transport_iscsi2]
[c0000000fd4c7740] c000000000370c9c .netlink_data_ready+0x40/0xa4
[c0000000fd4c77c0] c00000000036f010 .netlink_sendskb+0x4c/0x9c
[c0000000fd4c7850] c000000000370c18 .netlink_sendmsg+0x358/0x39c
[c0000000fd4c7950] c00000000033be24 .sock_sendmsg+0x114/0x1b8
[c0000000fd4c7b50] c00000000033d208 .sys_sendmsg+0x218/0x2ac
[c0000000fd4c7d70] c00000000033f55c .sys_socketcall+0x228/0x27c
[c0000000fd4c7e30] c0000000000086a4 syscall_exit+0x0/0x40
diff --git a/drivers/net/cxgb3/l2t.c b/drivers/net/cxgb3/l2t.c
index f452c40..4154097 100644
--- a/drivers/net/cxgb3/l2t.c
+++ b/drivers/net/cxgb3/l2t.c
@@ -300,14 +300,21 @@
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;
+ 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;
+ rcu_read_lock();
+ d = L2DATA(cdev);
+ 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 &&
@@ -338,6 +345,8 @@
}
done:
write_unlock_bh(&d->lock);
+done_rcu:
+ rcu_read_unlock();
return e;
}