IB/core: Fix possible crash to access NULL netdev

resolved_dev returned might be NULL as ifindex is transient number.
Ignoring NULL check of resolved_dev might crash the kernel.
Therefore perform NULL check before accessing resolved_dev.

Additionally rdma_resolve_ip_route() invokes addr_resolve() which
performs check and address translation for loopback ifindex.
Therefore, checking it again in rdma_resolve_ip_route() is not helpful.
Therefore, the code is simplified to avoid IFF_LOOPBACK check.

Fixes: 200298326b27 ("IB/core: Validate route when we init ah")
Reviewed-by: Daniel Jurgens <danielj@mellanox.com>
Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>

1 files changed, 3 insertions, 4 deletions

diff --git a/drivers/infiniband/core/sa_query.c b/drivers/infiniband/core/sa_query.c
index 8cf15d4a8ac4..9f029a1ca5ea 100644
--- a/drivers/infiniband/core/sa_query.c
+++ b/drivers/infiniband/core/sa_query.c
@@ -1291,10 +1291,9 @@ int ib_init_ah_attr_from_path(struct ib_device *device, u8 port_num,
 
                 resolved_dev = dev_get_by_index(dev_addr.net,
                                                 dev_addr.bound_dev_if);
-                if (resolved_dev->flags & IFF_LOOPBACK) {
-                        dev_put(resolved_dev);
-                        resolved_dev = idev;
-                        dev_hold(resolved_dev);
+                if (!resolved_dev) {
+                        dev_put(idev);
+                        return -ENODEV;
                 }
                 ndev = ib_get_ndev_from_path(rec);
                 rcu_read_lock();