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bpf: btf: Use exact btf value_size match in map_check_btf()

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The current map_check_btf() in BPF_MAP_TYPE_ARRAY rejects
'> map->value_size' to ensure map_seq_show_elem() will not
access things beyond an array element.

Yonghong suggested that using '!=' is a more correct
check.  The 8 bytes round_up on value_size is stored
in array->elem_size.  Hence, using '!=' on map->value_size
is a proper check.

This patch also adds new tests to check the btf array
key type and value type.  Two of these new tests verify
the btf's value_size (the change in this patch).

It also fixes two existing tests that wrongly encoded
a btf's type size (pprint_test) and the value_type_id (in one
of the raw_tests[]).  However, that do not affect these two
BTF verification tests before or after this test changes.
These two tests mainly failed at array creation time after
this patch.

Fixes: a26ca7c982 ("bpf: btf: Add pretty print support to the basic arraymap")
Suggested-by: Yonghong Song <yhs@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Martin KaFai Lau 2018-07-26 09:57:59 -07:00 • committed by Daniel Borkmann
parent 36e0f12bbf
commit 5f300e8004
2 changed files with 85 additions and 3 deletions
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2
kernel/bpf/arraymap.c
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@ -378,7 +378,7 @@ static int array_map_check_btf(const struct bpf_map *map, const struct btf *btf,
return -EINVAL;
value_type = btf_type_id_size(btf, &btf_value_id, &value_size);
if (!value_type || value_size > map->value_size)
if (!value_type || value_size != map->value_size)
return -EINVAL;
return 0;