[PATCH] bpf: add missing NULL check for __dev_get_by_index

[Qasim Ijaz <qasdev00@gmail.com>]

The __dev_get_by_index function can return NULL if it fails to 
find a device with the provided ifindex.

We should handle this case by adding a NULL check
and cleaning up if it does happened.

Signed-off-by: Qasim Ijaz <qasdev00@gmail.com>
Fixes: a38845729ea3 ("bpf: offload: add map offload infrastructure")
---
 kernel/bpf/offload.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/kernel/bpf/offload.c b/kernel/bpf/offload.c
index a10153c3be2d..28a30fa4457a 100644
--- a/kernel/bpf/offload.c
+++ b/kernel/bpf/offload.c
@@ -530,6 +530,12 @@ struct bpf_map *bpf_map_offload_map_alloc(union bpf_attr *attr)
 	bpf_map_init_from_attr(&offmap->map, attr);
 	rtnl_lock();
 	offmap->netdev = __dev_get_by_index(net, attr->map_ifindex);
+	if (!offmap->netdev) {
+		rtnl_unlock();
+		bpf_map_area_free(offmap);
+		return ERR_PTR(-ENODEV);
+	}	
+
 	netdev_lock_ops(offmap->netdev);
 	down_write(&bpf_devs_lock);
 	err = bpf_dev_offload_check(offmap->netdev);
-- 
2.39.5