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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 <martin.lau@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Yonghong Song <yhs@fb.com> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20221221013036.3427431-1-martin.lau@linux.dev
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@ -580,8 +580,8 @@ static struct bpf_local_storage_map *__bpf_local_storage_map_alloc(union bpf_att
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raw_spin_lock_init(&smap->buckets[i].lock);
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}
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smap->elem_size =
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sizeof(struct bpf_local_storage_elem) + attr->value_size;
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smap->elem_size = offsetof(struct bpf_local_storage_elem,
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sdata.data[attr->value_size]);
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return smap;
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}
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