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References: <20210419155243.1632274-1-revest@chromium.org> <20210419155243.1632274-7-revest@chromium.org>
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From:   Andrii Nakryiko <andrii.nakryiko@gmail.com>
Date:   Fri, 23 Apr 2021 15:38:11 -0700
Message-ID: <CAEf4BzZUM4hb9owhompwARabRvRbCYxBrpgXSdXM8RRm42tU1A@mail.gmail.com>
Subject: Re: [PATCH bpf-next v5 6/6] selftests/bpf: Add a series of tests for bpf_snprintf
To:     Florent Revest <revest@chromium.org>
Cc:     bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Yonghong Song <yhs@fb.com>, KP Singh <kpsingh@kernel.org>,
        Brendan Jackman <jackmanb@chromium.org>,
        open list <linux-kernel@vger.kernel.org>
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On Mon, Apr 19, 2021 at 8:52 AM Florent Revest <revest@chromium.org> wrote:
>
> The "positive" part tests all format specifiers when things go well.
>
> The "negative" part makes sure that incorrect format strings fail at
> load time.
>
> Signed-off-by: Florent Revest <revest@chromium.org>
> ---
>  .../selftests/bpf/prog_tests/snprintf.c       | 125 ++++++++++++++++++
>  .../selftests/bpf/progs/test_snprintf.c       |  73 ++++++++++
>  .../bpf/progs/test_snprintf_single.c          |  20 +++
>  3 files changed, 218 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/snprintf.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_snprintf.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_snprintf_single.c
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/snprintf.c b/tools/testing/selftests/bpf/prog_tests/snprintf.c
> new file mode 100644
> index 000000000000..a958c22aec75
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/snprintf.c
> @@ -0,0 +1,125 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2021 Google LLC. */
> +
> +#include <test_progs.h>
> +#include "test_snprintf.skel.h"
> +#include "test_snprintf_single.skel.h"
> +
> +#define EXP_NUM_OUT  "-8 9 96 -424242 1337 DABBAD00"
> +#define EXP_NUM_RET  sizeof(EXP_NUM_OUT)
> +
> +#define EXP_IP_OUT   "127.000.000.001 0000:0000:0000:0000:0000:0000:0000:0001"
> +#define EXP_IP_RET   sizeof(EXP_IP_OUT)
> +
> +/* The third specifier, %pB, depends on compiler inlining so don't check it */
> +#define EXP_SYM_OUT  "schedule schedule+0x0/"
> +#define MIN_SYM_RET  sizeof(EXP_SYM_OUT)
> +
> +/* The third specifier, %p, is a hashed pointer which changes on every reboot */
> +#define EXP_ADDR_OUT "0000000000000000 ffff00000add4e55 "
> +#define EXP_ADDR_RET sizeof(EXP_ADDR_OUT "unknownhashedptr")
> +
> +#define EXP_STR_OUT  "str1 longstr"
> +#define EXP_STR_RET  sizeof(EXP_STR_OUT)
> +
> +#define EXP_OVER_OUT "%over"
> +#define EXP_OVER_RET 10
> +
> +#define EXP_PAD_OUT "    4 000"

Roughly 50% of the time I get failure for this test case:

test_snprintf_positive:FAIL:pad_out unexpected pad_out: actual '    4
0000' != expected '    4 000'

Re-running this test case immediately passes. Running again most
probably fails. Please take a look.

> +#define EXP_PAD_RET 900007
> +
> +#define EXP_NO_ARG_OUT "simple case"
> +#define EXP_NO_ARG_RET 12
> +
> +#define EXP_NO_BUF_RET 29
> +

[...]