bpf: Fix range_tree_set() error handling

range_tree_set() might fail and return -ENOMEM,
causing subsequent `bpf_arena_alloc_pages` to fail.
Add the error handling.

Signed-off-by: Soma Nakata <soma.nakata@somane.sakura.ne.jp>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250106231536.52856-1-soma.nakata@somane.sakura.ne.jp
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Author: Soma Nakata

kernel/bpf/arena.c

@@ -138,7 +138,11 @@ static struct bpf_map *arena_map_alloc(union bpf_attr *attr)
 	INIT_LIST_HEAD(&arena->vma_list);
 	bpf_map_init_from_attr(&arena->map, attr);
 	range_tree_init(&arena->rt);
-	range_tree_set(&arena->rt, 0, attr->max_entries);
+	err = range_tree_set(&arena->rt, 0, attr->max_entries);
+	if (err) {
+		bpf_map_area_free(arena);
+		goto err;
+	}
 	mutex_init(&arena->lock);
 
 	return &arena->map;