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bpf: Reduce smap->elem_size

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[ Upstream commit 552d42a356ebf78df9d2f4b73e077d2459966fac ]

'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
Stable-dep-of: af253aef183a ("bpf: fix order of args in call to bpf_map_kvcalloc")
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Martin KaFai Lau 2022-12-20 17:30:36 -08:00 committed by Greg Kroah-Hartman
parent 3dbcc6f053
commit 56161b324b
1 changed files with 2 additions and 2 deletions
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4
kernel/bpf/bpf_local_storage.c
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@ -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;
}