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Date:   Tue, 17 Jan 2023 08:22:01 -0800
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Subject: Re: [PATCH] tools: bpf: Disable stack protector
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To:     Peter Foley <pefoley2@pefoley.com>
Cc:     Eduard Zingerman <eddyz87@gmail.com>,
        Quentin Monnet <quentin@isovalent.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <martin.lau@linux.dev>,
        Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>,
        Stanislav Fomichev <sdf@google.com>,
        Hao Luo <haoluo@google.com>, Jiri Olsa <jolsa@kernel.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Tom Rix <trix@redhat.com>, bpf@vger.kernel.org,
        linux-kernel@vger.kernel.org, llvm@lists.linux.dev,
        "Jose E. Marchesi" <jose.marchesi@oracle.com>
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From:   Yonghong Song <yhs@meta.com>
In-Reply-To: <CAOFdcFPnHEc2qd-=C+hdK4nTjJfbHsf4r-G7pdJTRBAT6MuOzg@mail.gmail.com>
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On 1/16/23 11:09 PM, Peter Foley wrote:
> On Mon, Jan 16, 2023 at 11:05 PM Yonghong Song <yhs@meta.com> wrote:
>>
>> If I understand correctly (by inspecting clang code), the stack
>> protector is off by default. Do you have link to Gentoo build
>> page to show how they enable stack protector? cmake config or
>> a private patch?
>>
> The relevant override appears to be
> https://github.com/gentoo/gentoo/blob/c5247250e9d4a09e67a602965a5f72be3cebbf34/sys-devel/clang-common/clang-common-15.0.7.ebuild#L93

Thanks for the link. Looks like this is a security feature added by 
hardened_gentoo progject (https://wiki.gentoo.org/wiki/Hardened_Gentoo)
which unconditionally added -fstack-protector-strong to the clang
compilation flag.