Re: [PATCH] arm64: bpf: fix div-by-zero case

From	Daniel Borkmann <daniel@iogearbox.net>
Newsgroups	linux.kernel
Subject	Re: [PATCH] arm64: bpf: fix div-by-zero case
Date	2015-11-04 20:40 +0100
Message-ID	<qrc4y-4EN-15@gated-at.bofh.it> (permalink)
References	<qr0d4-5pG-7@gated-at.bofh.it> <qr0mJ-5J7-5@gated-at.bofh.it> <qraYO-411-27@gated-at.bofh.it> <qrbi9-47z-11@gated-at.bofh.it> <qrbi9-47z-9@gated-at.bofh.it>
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On 11/04/2015 07:41 PM, Shi, Yang wrote:
...
>>> Agreed, and we may need add one more test cases in test_bpf module to cover
>>> MOD?
>>
>> Let me know if you have a test case ready :)
>
> Does the below change look like a valid test?
>
> +               "MOD default X",
> +               .u.insns = {
> +                       /*
> +                        * A = 0x42
> +                        * A = A mod X ; this halt the filter execution if X is 0
> +                        * ret 0x42
> +                        */
> +                       BPF_STMT(BPF_LD | BPF_IMM, 0x42),
> +                       BPF_STMT(BPF_ALU | BPF_MOD | BPF_X, 0),
> +                       BPF_STMT(BPF_RET | BPF_K, 0x42),
> +               },
> +               CLASSIC | FLAG_NO_DATA,
> +               {},
> +               { {0x1, 0x0 } },
> +       },
> +       {
> +               "MOD default A",
> +               .u.insns = {
> +                       /*
> +                        * A = A mod 1
> +                        * ret A
> +                        */
> +                       BPF_STMT(BPF_ALU | BPF_MOD | BPF_K, 0x1),
> +                       BPF_STMT(BPF_RET | BPF_A, 0x0),
> +               },
> +               CLASSIC | FLAG_NO_DATA,
> +               {},
> +               { {0x1, 0x0 } },
> +       },
>
> My test result with it:
> test_bpf: #284 MOD default X jited:1 ret 66 != 0 FAIL (1 times)
> test_bpf: #285 MOD default A jited:1 102 PASS
>
> If it looks right, I will post a patch to add the test cases.

Looks good to me.

Thanks,
Daniel
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Thread

[PATCH] arm64: bpf: fix div-by-zero case Zi Shen Lim <zlim.lnx@gmail.com> - 2015-11-04 08:00 +0100
  Re: [PATCH] arm64: bpf: fix div-by-zero case Xi Wang <xi.wang@gmail.com> - 2015-11-04 08:10 +0100
    Re: [PATCH] arm64: bpf: fix div-by-zero case "Shi, Yang" <yang.shi@linaro.org> - 2015-11-04 19:30 +0100
      Re: [PATCH] arm64: bpf: fix div-by-zero case "Shi, Yang" <yang.shi@linaro.org> - 2015-11-04 19:50 +0100
        Re: [PATCH] arm64: bpf: fix div-by-zero case Daniel Borkmann <daniel@iogearbox.net> - 2015-11-04 20:40 +0100
      Re: [PATCH] arm64: bpf: fix div-by-zero case Z Lim <zlim.lnx@gmail.com> - 2015-11-04 20:00 +0100
  Re: [PATCH] arm64: bpf: fix div-by-zero case "Shi, Yang" <yang.shi@linaro.org> - 2015-11-04 19:10 +0100

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