bpf: increase verifier log limit

The existing 16Mbyte verifier log limit is not enough for log_level=2
even for small programs. Increase it to 1Gbyte.
Note it's not a kernel memory limit.
It's an amount of memory user space provides to store
the verifier log. The kernel populates it 1k at a time.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

kernel/bpf/verifier.c

@@ -7974,7 +7974,7 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr,
 
 		ret = -EINVAL;
 		/* log attributes have to be sane */
-		if (log->len_total < 128 || log->len_total > UINT_MAX >> 8 ||
+		if (log->len_total < 128 || log->len_total > UINT_MAX >> 2 ||
 		    !log->level || !log->ubuf || log->level & ~BPF_LOG_MASK)
 			goto err_unlock;
 	}