scsi: libcxgbi: add a check for NULL pointer in cxgbi_check_route()

BugLink: https://bugs.launchpad.net/bugs/1836666

[ Upstream commit cc555759 ]

ip_dev_find() can return NULL so add a check for NULL pointer.
Signed-off-by: Varun Prakash <varun@chelsio.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/scsi/cxgbi/libcxgbi.c

@@ -634,6 +634,10 @@ static struct cxgbi_sock *cxgbi_check_route(struct sockaddr *dst_addr)
 
 	if (ndev->flags & IFF_LOOPBACK) {
 		ndev = ip_dev_find(&init_net, daddr->sin_addr.s_addr);
+		if (!ndev) {
+			err = -ENETUNREACH;
+			goto rel_neigh;
+		}
 		mtu = ndev->mtu;
 		pr_info("rt dev %s, loopback -> %s, mtu %u.\n",
 			n->dev->name, ndev->name, mtu);