IB: Fix RCU lockdep splats

Commit f2c31e32b37 ("net: fix NULL dereferences in check_peer_redir()")
forgot to take care of infiniband uses of dst neighbours.

Many thanks to Marc Aurele who provided a nice bug report and feedback.

Reported-by: Marc Aurele La France <tsi@ualberta.ca>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: David Miller <davem@davemloft.net>
Cc: <stable@kernel.org>
Signed-off-by: Roland Dreier <roland@purestorage.com>

6 files changed, 35 insertions, 14 deletions

diff --git a/drivers/infiniband/core/addr.c b/drivers/infiniband/core/addr.c
index 691276bafd78..e9cf51b1343b 100644
--- a/drivers/infiniband/core/addr.c
+++ b/drivers/infiniband/core/addr.c
@@ -216,7 +216,9 @@ static int addr4_resolve(struct sockaddr_in *src_in,
 
         neigh = neigh_lookup(&arp_tbl, &rt->rt_gateway, rt->dst.dev);
         if (!neigh || !(neigh->nud_state & NUD_VALID)) {
+                rcu_read_lock();
                 neigh_event_send(dst_get_neighbour(&rt->dst), NULL);
+                rcu_read_unlock();
                 ret = -ENODATA;
                 if (neigh)
                         goto release;
@@ -274,15 +276,16 @@ static int addr6_resolve(struct sockaddr_in6 *src_in,
                 goto put;
         }
 
+        rcu_read_lock();
         neigh = dst_get_neighbour(dst);
         if (!neigh || !(neigh->nud_state & NUD_VALID)) {
                 if (neigh)
                         neigh_event_send(neigh, NULL);
                 ret = -ENODATA;
-                goto put;
+        } else {
+                ret = rdma_copy_addr(addr, dst->dev, neigh->ha);
         }
-
-        ret = rdma_copy_addr(addr, dst->dev, neigh->ha);
+        rcu_read_unlock();
 put:
         dst_release(dst);
         return ret;
diff --git a/drivers/infiniband/hw/cxgb3/iwch_cm.c b/drivers/infiniband/hw/cxgb3/iwch_cm.c
index de6d0774e609..c88b12beef25 100644
--- a/drivers/infiniband/hw/cxgb3/iwch_cm.c
+++ b/drivers/infiniband/hw/cxgb3/iwch_cm.c
@@ -1375,8 +1375,10 @@ static int pass_accept_req(struct t3cdev *tdev, struct sk_buff *skb, void *ctx)
                 goto reject;
         }
         dst = &rt->dst;
+        rcu_read_lock();
         neigh = dst_get_neighbour(dst);
         l2t = t3_l2t_get(tdev, neigh, neigh->dev);
+        rcu_read_unlock();
         if (!l2t) {
                 printk(KERN_ERR MOD "%s - failed to allocate l2t entry!\n",
                        __func__);
@@ -1946,10 +1948,12 @@ int iwch_connect(struct iw_cm_id *cm_id, struct iw_cm_conn_param *conn_param)
         }
         ep->dst = &rt->dst;
 
+        rcu_read_lock();
         neigh = dst_get_neighbour(ep->dst);
 
         /* get a l2t entry */
         ep->l2t = t3_l2t_get(ep->com.tdev, neigh, neigh->dev);
+        rcu_read_unlock();
         if (!ep->l2t) {
                 printk(KERN_ERR MOD "%s - cannot alloc l2e.\n", __func__);
                 err = -ENOMEM;
diff --git a/drivers/infiniband/hw/cxgb4/cm.c b/drivers/infiniband/hw/cxgb4/cm.c
index b36cdac9c558..75b57bee6622 100644
--- a/drivers/infiniband/hw/cxgb4/cm.c
+++ b/drivers/infiniband/hw/cxgb4/cm.c
@@ -1594,6 +1594,7 @@ static int pass_accept_req(struct c4iw_dev *dev, struct sk_buff *skb)
                 goto reject;
         }
         dst = &rt->dst;
+        rcu_read_lock();
         neigh = dst_get_neighbour(dst);
         if (neigh->dev->flags & IFF_LOOPBACK) {
                 pdev = ip_dev_find(&init_net, peer_ip);
@@ -1620,6 +1621,7 @@ static int pass_accept_req(struct c4iw_dev *dev, struct sk_buff *skb)
                 rss_qid = dev->rdev.lldi.rxq_ids[
                           cxgb4_port_idx(neigh->dev) * step];
         }
+        rcu_read_unlock();
         if (!l2t) {
                 printk(KERN_ERR MOD "%s - failed to allocate l2t entry!\n",
                        __func__);
@@ -1820,6 +1822,7 @@ static int c4iw_reconnect(struct c4iw_ep *ep)
         }
         ep->dst = &rt->dst;
 
+        rcu_read_lock();
         neigh = dst_get_neighbour(ep->dst);
 
         /* get a l2t entry */
@@ -1856,6 +1859,7 @@ static int c4iw_reconnect(struct c4iw_ep *ep)
                 ep->rss_qid = ep->com.dev->rdev.lldi.rxq_ids[
                         cxgb4_port_idx(neigh->dev) * step];
         }
+        rcu_read_unlock();
         if (!ep->l2t) {
                 printk(KERN_ERR MOD "%s - cannot alloc l2e.\n", __func__);
                 err = -ENOMEM;
@@ -2301,6 +2305,7 @@ int c4iw_connect(struct iw_cm_id *cm_id, struct iw_cm_conn_param *conn_param)
         }
         ep->dst = &rt->dst;
 
+        rcu_read_lock();
         neigh = dst_get_neighbour(ep->dst);
 
         /* get a l2t entry */
@@ -2339,6 +2344,7 @@ int c4iw_connect(struct iw_cm_id *cm_id, struct iw_cm_conn_param *conn_param)
                 ep->retry_with_mpa_v1 = 0;
                 ep->tried_with_mpa_v1 = 0;
         }
+        rcu_read_unlock();
         if (!ep->l2t) {
                 printk(KERN_ERR MOD "%s - cannot alloc l2e.\n", __func__);
                 err = -ENOMEM;
diff --git a/drivers/infiniband/hw/nes/nes_cm.c b/drivers/infiniband/hw/nes/nes_cm.c
index dfce9ea98a39..0a52d72371ee 100644
--- a/drivers/infiniband/hw/nes/nes_cm.c
+++ b/drivers/infiniband/hw/nes/nes_cm.c
@@ -1377,9 +1377,11 @@ static int nes_addr_resolve_neigh(struct nes_vnic *nesvnic, u32 dst_ip, int arpi
                 neigh_release(neigh);
         }
 
-        if ((neigh == NULL) || (!(neigh->nud_state & NUD_VALID)))
+        if ((neigh == NULL) || (!(neigh->nud_state & NUD_VALID))) {
+                rcu_read_lock();
                 neigh_event_send(dst_get_neighbour(&rt->dst), NULL);
-
+                rcu_read_unlock();
+        }
         ip_rt_put(rt);
         return rc;
 }
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_main.c b/drivers/infiniband/ulp/ipoib/ipoib_main.c
index 7567b6000230..ef38848d1b0e 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_main.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_main.c
@@ -555,6 +555,7 @@ static int path_rec_start(struct net_device *dev,
         return 0;
 }
 
+/* called with rcu_read_lock */
 static void neigh_add_path(struct sk_buff *skb, struct net_device *dev)
 {
         struct ipoib_dev_priv *priv = netdev_priv(dev);
@@ -636,6 +637,7 @@ err_drop:
         spin_unlock_irqrestore(&priv->lock, flags);
 }
 
+/* called with rcu_read_lock */
 static void ipoib_path_lookup(struct sk_buff *skb, struct net_device *dev)
 {
         struct ipoib_dev_priv *priv = netdev_priv(skb->dev);
@@ -720,13 +722,14 @@ static int ipoib_start_xmit(struct sk_buff *skb, struct net_device *dev)
         struct neighbour *n = NULL;
         unsigned long flags;
 
+        rcu_read_lock();
         if (likely(skb_dst(skb)))
                 n = dst_get_neighbour(skb_dst(skb));
 
         if (likely(n)) {
                 if (unlikely(!*to_ipoib_neigh(n))) {
                         ipoib_path_lookup(skb, dev);
-                        return NETDEV_TX_OK;
+                        goto unlock;
                 }
 
                 neigh = *to_ipoib_neigh(n);
@@ -749,17 +752,17 @@ static int ipoib_start_xmit(struct sk_buff *skb, struct net_device *dev)
                         ipoib_neigh_free(dev, neigh);
                         spin_unlock_irqrestore(&priv->lock, flags);
                         ipoib_path_lookup(skb, dev);
-                        return NETDEV_TX_OK;
+                        goto unlock;
                 }
 
                 if (ipoib_cm_get(neigh)) {
                         if (ipoib_cm_up(neigh)) {
                                 ipoib_cm_send(dev, skb, ipoib_cm_get(neigh));
-                                return NETDEV_TX_OK;
+                                goto unlock;
                         }
                 } else if (neigh->ah) {
                         ipoib_send(dev, skb, neigh->ah, IPOIB_QPN(n->ha));
-                        return NETDEV_TX_OK;
+                        goto unlock;
                 }
 
                 if (skb_queue_len(&neigh->queue) < IPOIB_MAX_PATH_REC_QUEUE) {
@@ -793,13 +796,14 @@ static int ipoib_start_xmit(struct sk_buff *skb, struct net_device *dev)
                                            phdr->hwaddr + 4);
                                 dev_kfree_skb_any(skb);
                                 ++dev->stats.tx_dropped;
-                                return NETDEV_TX_OK;
+                                goto unlock;
                         }
 
                         unicast_arp_send(skb, dev, phdr);
                 }
         }
-
+unlock:
+        rcu_read_unlock();
         return NETDEV_TX_OK;
 }
 
@@ -837,7 +841,7 @@ static int ipoib_hard_header(struct sk_buff *skb,
         dst = skb_dst(skb);
         n = NULL;
         if (dst)
-                n = dst_get_neighbour(dst);
+                n = dst_get_neighbour_raw(dst);
         if ((!dst || !n) && daddr) {
                 struct ipoib_pseudoheader *phdr =
                         (struct ipoib_pseudoheader *) skb_push(skb, sizeof *phdr);
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_multicast.c b/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
index 1b7a97686356..cad1894594a8 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_multicast.c
@@ -266,7 +266,7 @@ static int ipoib_mcast_join_finish(struct ipoib_mcast *mcast,
 
                 skb->dev = dev;
                 if (dst)
-                        n = dst_get_neighbour(dst);
+                        n = dst_get_neighbour_raw(dst);
                 if (!dst || !n) {
                         /* put pseudoheader back on for next time */
                         skb_push(skb, sizeof (struct ipoib_pseudoheader));
@@ -722,6 +722,8 @@ out:
         if (mcast && mcast->ah) {
                 struct dst_entry *dst = skb_dst(skb);
                 struct neighbour *n = NULL;
+
+                rcu_read_lock();
                 if (dst)
                         n = dst_get_neighbour(dst);
                 if (n && !*to_ipoib_neigh(n)) {
@@ -734,7 +736,7 @@ out:
                                 list_add_tail(&neigh->list, &mcast->neigh_list);
                         }
                 }
-
+                rcu_read_unlock();
                 spin_unlock_irqrestore(&priv->lock, flags);
                 ipoib_send(dev, skb, mcast->ah, IB_MULTICAST_QPN);
                 return;