bpftool: Don't crash on missing xlated program instructions

commit d95f1e8b462c4372ac409886070bb8719d8a4d3a upstream.

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 <toke@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20200206102906.112551-1-toke@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index ea0bcd5..2e38842 100644 (file)
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -500,7 +500,7 @@ static int do_dump(int argc, char **argv)
                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?");
                        goto err_free;
                }