From: Martin KaFai Lau <martin.lau@xxxxxxxxxx> 'struct bpf_local_storage_elem' has an unused 56 byte padding at the end due to struct's cache-line alignment requirement. This padding space is overlapped by storage value contents, so if we use sizeof() to calculate the total size, we overinflate it by 56 bytes. Use offsetof() instead to calculate more exact memory use. Acked-by: Yonghong Song <yhs@xxxxxx> Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx> Signed-off-by: Martin KaFai Lau <martin.lau@xxxxxxxxxx> --- v3: Use one offsetof and save a '+' operator (Andrii) v2: Rephrase the commit message (Andrii and Yonghong) Use offsetofend instead of offsetof (Andrii) kernel/bpf/bpf_local_storage.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/bpf/bpf_local_storage.c b/kernel/bpf/bpf_local_storage.c index b39a46e8fb08..373c3c2c75bc 100644 --- a/kernel/bpf/bpf_local_storage.c +++ b/kernel/bpf/bpf_local_storage.c @@ -580,8 +580,8 @@ static struct bpf_local_storage_map *__bpf_local_storage_map_alloc(union bpf_att raw_spin_lock_init(&smap->buckets[i].lock); } - smap->elem_size = - sizeof(struct bpf_local_storage_elem) + attr->value_size; + smap->elem_size = offsetof(struct bpf_local_storage_elem, + sdata.data[attr->value_size]); return smap; } -- 2.30.2
