bpf: Use struct_size() helper

In an effort to avoid open-coded arithmetic in the kernel, use the
struct_size() helper instead of open-coded calculation.

Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://github.com/KSPP/linux/issues/160
Link: https://lore.kernel.org/bpf/20211220113048.2859-1-xiujianfeng@huawei.com

diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c
index 035e9e3..23f7f9d 100644 (file)
--- a/kernel/bpf/local_storage.c
+++ b/kernel/bpf/local_storage.c
@@ -163,8 +163,7 @@ static int cgroup_storage_update_elem(struct bpf_map *map, void *key,
                return 0;
        }
 
-       new = bpf_map_kmalloc_node(map, sizeof(struct bpf_storage_buffer) +
-                                  map->value_size,
+       new = bpf_map_kmalloc_node(map, struct_size(new, data, map->value_size),
                                   __GFP_ZERO | GFP_ATOMIC | __GFP_NOWARN,
                                   map->numa_node);
        if (!new)

diff --git a/kernel/bpf/reuseport_array.c b/kernel/bpf/reuseport_array.c
index 93a5539..556a769 100644 (file)
--- a/kernel/bpf/reuseport_array.c
+++ b/kernel/bpf/reuseport_array.c
@@ -152,16 +152,12 @@ static struct bpf_map *reuseport_array_alloc(union bpf_attr *attr)
 {
        int numa_node = bpf_map_attr_numa_node(attr);
        struct reuseport_array *array;
-       u64 array_size;
 
        if (!bpf_capable())
                return ERR_PTR(-EPERM);
 
-       array_size = sizeof(*array);
-       array_size += (u64)attr->max_entries * sizeof(struct sock *);
-
        /* allocate all map elements and zero-initialize them */
-       array = bpf_map_area_alloc(array_size, numa_node);
+       array = bpf_map_area_alloc(struct_size(array, ptrs, attr->max_entries), numa_node);
        if (!array)
                return ERR_PTR(-ENOMEM);