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Subject[PATCH AUTOSEL 4.19 14/52] i40iw: Avoid panic when handling the inetdev event
Date
From: Feng Tang <feng.tang@intel.com>

[ 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.tang@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Sasha Levin <sashal@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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