bpf: devmap: pass on return value of bpf_map_precharge_memlock

If bpf_map_precharge_memlock in dev_map_alloc, -ENOMEM is returned
regardless of the actual error produced by bpf_map_precharge_memlock.
Fix it by passing on the error returned by bpf_map_precharge_memlock.

Also return -EINVAL instead of -ENOMEM if the page count overflow check
fails.

This makes dev_map_alloc match the behavior of other bpf maps' alloc
functions wrt. return values.
Signed-off-by: NTobias Klauser <tklauser@distanz.ch>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

kernel/bpf/devmap.c

@@ -75,8 +75,8 @@ static u64 dev_map_bitmap_size(const union bpf_attr *attr)
 static struct bpf_map *dev_map_alloc(union bpf_attr *attr)
 {
 	struct bpf_dtab *dtab;
+	int err = -EINVAL;
 	u64 cost;
-	int err;
 
 	/* check sanity of attributes */
 	if (attr->max_entries == 0 || attr->key_size != 4 ||
@@ -108,6 +108,8 @@ 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(dev_map_bitmap_size(attr),
 					    __alignof__(unsigned long));
@@ -128,7 +130,7 @@ static struct bpf_map *dev_map_alloc(union bpf_attr *attr)
 free_dtab:
 	free_percpu(dtab->flush_needed);
 	kfree(dtab);
-	return ERR_PTR(-ENOMEM);
+	return ERR_PTR(err);
 }
 
 static void dev_map_free(struct bpf_map *map)