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([2001:1620:665:0:d4b6:f719:ed17:25fe]) by smtp.gmail.com with ESMTPSA id o4sm47088wrw.15.2020.02.06.09.52.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 06 Feb 2020 09:52:22 -0800 (PST) Subject: Re: [PATCH bpf] bpftool: Don't crash on missing xlated program instructions To: =?UTF-8?Q?Toke_H=c3=b8iland-J=c3=b8rgensen?= , daniel@iogearbox.net, ast@fb.com Cc: bpf@vger.kernel.org, netdev@vger.kernel.org References: <20200206102906.112551-1-toke@redhat.com> From: Quentin Monnet Message-ID: <3faff584-3139-9ff1-c083-c0c4569fa81c@isovalent.com> Date: Thu, 6 Feb 2020 17:52:20 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.2 MIME-Version: 1.0 In-Reply-To: <20200206102906.112551-1-toke@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 8bit Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org 2020-02-06 11:29 UTC+0100 ~ Toke Høiland-Jørgensen > Turns out the xlated program instructions can also be missing if > kptr_restrict sysctl is set. This means that the previous fix to check the > jited_prog_insns pointer was insufficient; add another check of the > xlated_prog_insns pointer as well. > > Fixes: 5b79bcdf0362 ("bpftool: Don't crash on missing jited insns or ksyms") > Fixes: cae73f233923 ("bpftool: use bpf_program__get_prog_info_linear() in prog.c:do_dump()") > Signed-off-by: Toke Høiland-Jørgensen > --- > tools/bpf/bpftool/prog.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c > index a3521deca869..b352ab041160 100644 > --- a/tools/bpf/bpftool/prog.c > +++ b/tools/bpf/bpftool/prog.c > @@ -536,7 +536,7 @@ prog_dump(struct bpf_prog_info *info, enum dump_mode mode, > buf = (unsigned char *)(info->jited_prog_insns); > member_len = info->jited_prog_len; > } else { /* DUMP_XLATED */ > - if (info->xlated_prog_len == 0) { > + if (info->xlated_prog_len == 0 || !info->xlated_prog_insns) { > p_err("error retrieving insn dump: kernel.kptr_restrict set?"); > return -1; > } > The fix looks good, thanks! Reviewed-by: Quentin Monnet