[PATCH 5.5 006/120] RDMA/i40iw: fix a potential NULL pointer dereference

[Greg Kroah-Hartman]

From: Xiyu Yang <xiyuyang19@xxxxxxxxxxxx>

commit 04db1580b5e48a79e24aa51ecae0cd4b2296ec23 upstream.

A NULL pointer can be returned by in_dev_get(). Thus add a corresponding
check so that a NULL pointer dereference will be avoided at this place.

Fixes: 8e06af711bf2 ("i40iw: add main, hdr, status")
Link: https://lore.kernel.org/r/1577672668-46499-1-git-send-email-xiyuyang19@xxxxxxxxxxxx
Signed-off-by: Xiyu Yang <xiyuyang19@xxxxxxxxxxxx>
Signed-off-by: Xin Tan <tanxin.ctf@xxxxxxxxx>
Reviewed-by: Leon Romanovsky <leonro@xxxxxxxxxxxx>
Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/infiniband/hw/i40iw/i40iw_main.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/infiniband/hw/i40iw/i40iw_main.c
+++ b/drivers/infiniband/hw/i40iw/i40iw_main.c
@@ -1225,6 +1225,8 @@ static void i40iw_add_ipv4_addr(struct i
 			const struct in_ifaddr *ifa;
 
 			idev = in_dev_get(dev);
+			if (!idev)
+				continue;
 			in_dev_for_each_ifa_rtnl(ifa, idev) {
 				i40iw_debug(&iwdev->sc_dev, I40IW_DEBUG_CM,
 					    "IP=%pI4, vlan_id=%d, MAC=%pM\n", &ifa->ifa_address,