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From:   Sami Tolvanen <samitolvanen@google.com>
Date:   Wed, 11 Sep 2019 13:29:56 -0700
Message-ID: <CABCJKueLLs7nUFnQ-BHWE3cPJncWACy2tG196n01QPpShUwKEg@mail.gmail.com>
Subject: Re: [PATCH] bpf: validate bpf_func when BPF_JIT is enabled
To:     Yonghong Song <yhs@fb.com>
Cc:     Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Kees Cook <keescook@chromium.org>, Martin Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "bpf@vger.kernel.org" <bpf@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= <toke@redhat.com>,
        =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= <bjorn.topel@intel.com>
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On Wed, Sep 11, 2019 at 12:43 AM Yonghong Song <yhs@fb.com> wrote:
> How about this:
>
>         if (!IS_ENABLED(CONFIG_BPF_JIT_ALWAYS_ON) && !prog->jited)
>                 goto out;
>
>         if (unlikely(hdr->magic != BPF_BINARY_HEADER_MAGIC ||
>             !arch_bpf_jit_check_func(prog))) {
>                 WARN(1, "attempt to jump to an invalid address");
>                 return 0;
>         }
> out:
>         return prog->bpf_func(ctx, prog->insnsi);

Sure, that does look cleaner. I'll use this in the next version. Thanks.

Sami