bpftool: Don't crash on missing xlated program instructions

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

diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index a3521deca86943aa93e24560b5aa7a47d1fb983d..b352ab041160746e4b61ce46b0a3eb2bb57cb8b0 100644 (file)
--- 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;
                }