[PATCH net-next] bpf: fix oops on allocation failure

[Dan Carpenter]

"err" is set to zero if bpf_map_area_alloc() fails so it means we return
ERR_PTR(0) which is NULL.  The caller, find_and_alloc_map(), is not
expecting NULL returns and will oops.

Fixes: 174a79ff9515 ("bpf: sockmap with sk redirect support")
Signed-off-by: Dan Carpenter <dan.carpen...@oracle.com>

diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c
index 78b2bb9370ac..a11b9f52ea4a 100644
--- a/kernel/bpf/sockmap.c
+++ b/kernel/bpf/sockmap.c
@@ -497,6 +497,7 @@ static struct bpf_map *sock_map_alloc(union bpf_attr *attr)
        if (err)
                goto free_stab;
 
+       err = -ENOMEM;
        stab->sock_map = bpf_map_area_alloc(stab->map.max_entries *
                                            sizeof(struct sock *),
                                            stab->map.numa_node);