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

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Message-ID: <1DBB9750-9262-4E2A-AE5E-59533C25B90E@fb.com>
Date:   Fri, 6 Nov 2020 00:19:58 +0000
From:   Song Liu <songliubraving@...com>
To:     Daniel Xu <dxu@...uu.xyz>
CC:     bpf <bpf@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "ast@...nel.org" <ast@...nel.org>,
        "daniel@...earbox.net" <daniel@...earbox.net>,
        "andrii.nakryiko@...il.com" <andrii.nakryiko@...il.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 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>

LGTM!

Acked-by: Song Liu <songliubraving@...com>

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