[PATCH net-next] bpf: dev_map_alloc() shouldn't return NULL

[Dan Carpenter]

We forgot to set the error code on two error paths which means that we
return ERR_PTR(0) which is NULL.  The caller, find_and_alloc_map(), is
not expecting that and will have a NULL dereference.

Fixes: 546ac1ffb70d ("bpf: add devmap, a map for storing net device references")
Signed-off-by: Dan Carpenter <dan.carpen...@oracle.com>

diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index 899364d097f5..d439ee0eadb1 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -114,6 +114,7 @@ static struct bpf_map *dev_map_alloc(union bpf_attr *attr)
        if (err)
                goto free_dtab;
 
+       err = -ENOMEM;
        /* A per cpu bitfield with a bit per possible net device */
        dtab->flush_needed = __alloc_percpu(
                                BITS_TO_LONGS(attr->max_entries) *