netdev - Re: [PATCH bpf] libbpf: fix SIGSEGV when BTF loading fails, but .BTF.ext exists

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Message-ID: <119053c1-5f18-3161-47c2-e39c2783d0d6@fb.com>
Date:   Fri, 19 Jul 2019 19:38:33 +0000
From:   Alexei Starovoitov <ast@...com>
To:     Andrii Nakryiko <andriin@...com>,
        "bpf@...r.kernel.org" <bpf@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "daniel@...earbox.net" <daniel@...earbox.net>,
        Andrey Ignatov <rdna@...com>
CC:     "andrii.nakryiko@...il.com" <andrii.nakryiko@...il.com>,
        Kernel Team <Kernel-team@...com>
Subject: Re: [PATCH bpf] libbpf: fix SIGSEGV when BTF loading fails, but
 .BTF.ext exists

On 7/19/19 12:32 PM, Andrii Nakryiko wrote:
> In case when BTF loading fails despite sanitization, but BPF object has
> .BTF.ext loaded as well, we free and null obj->btf, but not
> obj->btf_ext. This leads to an attempt to relocate .BTF.ext later on
> during bpf_object__load(), which assumes obj->btf is present. This leads
> to SIGSEGV on null pointer access. Fix bug by freeing and nulling
> obj->btf_ext as well.
> 
> Signed-off-by: Andrii Nakryiko <andriin@...com>

Applied. Thanks