IB/core: Fix possible crash to access NULL netdev

[ Upstream commit bb7f8f199c354c4cf155b1d6d55f86eaaed7fa5a ]

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>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/infiniband/core/sa_query.c b/drivers/infiniband/core/sa_query.c
index 81b742ca163911f3cfe6ffc42ea624931e7f3089..4baf3b864a576e2952d907215a6e98504821de45 100644 (file)
--- a/drivers/infiniband/core/sa_query.c
+++ b/drivers/infiniband/core/sa_query.c
@@ -1137,10 +1137,9 @@ int ib_init_ah_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();