From 552d42a356ebf78df9d2f4b73e077d2459966fac Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Tue, 20 Dec 2022 17:30:36 -0800 Subject: bpf: Reduce smap->elem_size '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. Signed-off-by: Martin KaFai Lau Signed-off-by: Daniel Borkmann Acked-by: Yonghong Song Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20221221013036.3427431-1-martin.lau@linux.dev --- kernel/bpf/bpf_local_storage.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel') 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; } -- cgit v1.2.3