[ Upstream commit ec4fe4bcc584b55e24e8d1768f5510a62c0fd619 ]

There is a panic reported that on a system with x722 ethernet, when doing
the operations like:

        # ip link add br0 type bridge
        # ip link set eno1 master br0
        # systemctl restart systemd-networkd

The system will panic "BUG: unable to handle kernel null pointer
dereference at 0000000000000034", with call chain:

        i40iw_inetaddr_event
        notifier_call_chain
        blocking_notifier_call_chain
        notifier_call_chain
        __inet_del_ifa
        inet_rtm_deladdr
        rtnetlink_rcv_msg
        netlink_rcv_skb
        rtnetlink_rcv
        netlink_unicast
        netlink_sendmsg
        sock_sendmsg
        __sys_sendto

It is caused by "local_ipaddr = ntohl(in->ifa_list->ifa_address)", while
the in->ifa_list is NULL.

So add a check for the "in->ifa_list == NULL" case, and skip the ARP
operation accordingly.

Signed-off-by: Feng Tang <feng.t...@intel.com>
Signed-off-by: Jason Gunthorpe <j...@mellanox.com>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
 drivers/infiniband/hw/i40iw/i40iw_utils.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/hw/i40iw/i40iw_utils.c 
b/drivers/infiniband/hw/i40iw/i40iw_utils.c
index a9ea966877f2..dda8e79d4b27 100644
--- a/drivers/infiniband/hw/i40iw/i40iw_utils.c
+++ b/drivers/infiniband/hw/i40iw/i40iw_utils.c
@@ -173,7 +173,12 @@ int i40iw_inetaddr_event(struct notifier_block *notifier,
 
                rcu_read_lock();
                in = __in_dev_get_rcu(upper_dev);
-               local_ipaddr = ntohl(in->ifa_list->ifa_address);
+
+               if (!in->ifa_list)
+                       local_ipaddr = 0;
+               else
+                       local_ipaddr = ntohl(in->ifa_list->ifa_address);
+
                rcu_read_unlock();
        } else {
                local_ipaddr = ntohl(ifa->ifa_address);
@@ -185,6 +190,11 @@ int i40iw_inetaddr_event(struct notifier_block *notifier,
        case NETDEV_UP:
                /* Fall through */
        case NETDEV_CHANGEADDR:
+
+               /* Just skip if no need to handle ARP cache */
+               if (!local_ipaddr)
+                       break;
+
                i40iw_manage_arp_cache(iwdev,
                                       netdev->dev_addr,
                                       &local_ipaddr,
-- 
2.19.1



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