IB/core: Fix use after free of ifa

When using ifup/ifdown while executing enum_netdev_ipv4_ips,
ifa could become invalid and cause use after free error.
Fixing it by protecting with RCU lock.

Fixes: 03db3a2d81e6 ('IB/core: Add RoCE GID table management')
Signed-off-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

1 files changed, 27 insertions, 8 deletions

diff --git a/drivers/infiniband/core/roce_gid_mgmt.c b/drivers/infiniband/core/roce_gid_mgmt.c
index 6b24cba1e474..178f98482e13 100644
--- a/drivers/infiniband/core/roce_gid_mgmt.c
+++ b/drivers/infiniband/core/roce_gid_mgmt.c
@@ -250,25 +250,44 @@ static void enum_netdev_ipv4_ips(struct ib_device *ib_dev,
                                  u8 port, struct net_device *ndev)
 {
         struct in_device *in_dev;
+        struct sin_list {
+                struct list_head        list;
+                struct sockaddr_in      ip;
+        };
+        struct sin_list *sin_iter;
+        struct sin_list *sin_temp;
 
+        LIST_HEAD(sin_list);
         if (ndev->reg_state >= NETREG_UNREGISTERING)
                 return;
 
-        in_dev = in_dev_get(ndev);
-        if (!in_dev)
+        rcu_read_lock();
+        in_dev = __in_dev_get_rcu(ndev);
+        if (!in_dev) {
+                rcu_read_unlock();
                 return;
+        }
 
         for_ifa(in_dev) {
-                struct sockaddr_in ip;
+                struct sin_list *entry = kzalloc(sizeof(*entry), GFP_ATOMIC);
 
-                ip.sin_family = AF_INET;
-                ip.sin_addr.s_addr = ifa->ifa_address;
-                update_gid_ip(GID_ADD, ib_dev, port, ndev,
-                              (struct sockaddr *)&ip);
+                if (!entry) {
+                        pr_warn("roce_gid_mgmt: couldn't allocate entry for IPv4 update\n");
+                        continue;
+                }
+                entry->ip.sin_family = AF_INET;
+                entry->ip.sin_addr.s_addr = ifa->ifa_address;
+                list_add_tail(&entry->list, &sin_list);
         }
         endfor_ifa(in_dev);
+        rcu_read_unlock();
 
-        in_dev_put(in_dev);
+        list_for_each_entry_safe(sin_iter, sin_temp, &sin_list, list) {
+                update_gid_ip(GID_ADD, ib_dev, port, ndev,
+                              (struct sockaddr *)&sin_iter->ip);
+                list_del(&sin_iter->list);
+                kfree(sin_iter);
+        }
 }
 
 static void enum_netdev_ipv6_ips(struct ib_device *ib_dev,