linux-kernel - Re: [PATCH bpf v4 2/2] selftest/bpf: Test bpf_probe_read_user

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Date:   Thu, 5 Nov 2020 19:53:05 -0800
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Daniel Xu <dxu@...uu.xyz>
Cc:     bpf <bpf@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Song Liu <songliubraving@...com>,
        Kernel Team <kernel-team@...com>
Subject: Re: [PATCH bpf v4 2/2] selftest/bpf: Test bpf_probe_read_user_str()
 strips trailing bytes after NUL

On Thu, Nov 5, 2020 at 4:06 PM Daniel Xu <dxu@...uu.xyz> wrote:
>
> Previously, bpf_probe_read_user_str() could potentially overcopy the
> trailing bytes after the NUL due to how do_strncpy_from_user() does the
> copy in long-sized strides. The issue has been fixed in the previous
> commit.
>
> This commit adds a selftest that ensures we don't regress
> bpf_probe_read_user_str() again.
>
> Signed-off-by: Daniel Xu <dxu@...uu.xyz>
> ---

Acked-by: Andrii Nakryiko <andrii@...nel.org>

>  .../bpf/prog_tests/probe_read_user_str.c      | 71 +++++++++++++++++++
>  .../bpf/progs/test_probe_read_user_str.c      | 25 +++++++
>  2 files changed, 96 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/probe_read_user_str.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_probe_read_user_str.c
>

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