bpf: additional sockmap self tests

Add some more sockmap tests to cover,

 - forwarding to NULL entries
 - more than two maps to test list ops
 - forwarding to different map

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/tools/testing/selftests/bpf/sockmap_parse_prog.c b/tools/testing/selftests/bpf/sockmap_parse_prog.c
index 710f43f..fae3b96 100644
--- a/tools/testing/selftests/bpf/sockmap_parse_prog.c
+++ b/tools/testing/selftests/bpf/sockmap_parse_prog.c
@@ -19,16 +19,16 @@ int bpf_prog1(struct __sk_buff *skb)
 	void *data = (void *)(long) skb->data;
 	__u32 lport = skb->local_port;
 	__u32 rport = skb->remote_port;
-	char *d = data;
+	__u8 *d = data;
 
-	if (data + 8 > data_end)
+	if (data + 10 > data_end)
 		return skb->len;
 
 	/* This write/read is a bit pointless but tests the verifier and
 	 * strparser handler for read/write pkt data and access into sk
 	 * fields.
 	 */
-	d[0] = 1;
+	d[7] = 1;
 
 	bpf_printk("parse: data[0] = (%u): local_port %i remote %i\n",
 		   d[0], lport, bpf_ntohl(rport));