netdev - Re: [PATCH bpf] bpf: btf: Use exact btf value_size match in map_check

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Message-ID: <32cdc385-c7a5-7e40-2d92-4ae8d370b782@iogearbox.net>
Date:   Fri, 27 Jul 2018 03:46:47 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Martin KaFai Lau <kafai@...com>, netdev@...r.kernel.org
Cc:     Alexei Starovoitov <ast@...com>, kernel-team@...com
Subject: Re: [PATCH bpf] bpf: btf: Use exact btf value_size match in
 map_check_btf()

On 07/26/2018 06:57 PM, Martin KaFai Lau wrote:
> 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: a26ca7c982cb ("bpf: btf: Add pretty print support to the basic arraymap")
> Suggested-by: Yonghong Song <yhs@...com>
> Acked-by: Yonghong Song <yhs@...com>
> Signed-off-by: Martin KaFai Lau <kafai@...com>

Applied to bpf, thanks Martin!