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 <[e-mail]>
Signed-off-by: Daniel Borkmann <[e-mail]>
Reviewed-by: Quentin Monnet <[e-mail]>
Link: https://lore.kernel.org/bpf/[e-mail]

tools/bpf/bpftool/prog.c

···
 		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;
 		}