commit f6d20e718131aa2b468ff0a6c42e20c0b900e58b
Author: Ilya Shipitsin <chipitsine@gmail.com>
Date:   Sat Sep 15 00:50:05 2018 +0500

    BUG/MINOR: connection: avoid null pointer dereference in send-proxy-v2
    
    found by coverity.
    
    [wt: this bug was introduced by commit 404d978 ("MINOR: add ALPN
     information to send-proxy-v2"). It might be triggered by a health
     check on a server using ppv2 or by an applet making use of such a
     server, if at all configurable].
    
    This needs to be backported to 1.8.
    
    (cherry picked from commit ca56fce8bd271928b18d38b439bd35bd273fe8d4)
    Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>

diff --git a/src/connection.c b/src/connection.c
index 8c5af156..7403e8ae 100644
--- a/src/connection.c
+++ b/src/connection.c
@@ -874,6 +874,7 @@ int conn_recv_netscaler_cip(struct connection *conn, int flag)
 	return 0;
 }
 
+/* Note: <remote> is explicitly allowed to be NULL */
 int make_proxy_line(char *buf, int buf_len, struct server *srv, struct connection *remote)
 {
 	int ret = 0;
@@ -985,6 +986,7 @@ static int make_tlv(char *dest, int dest_len, char type, uint16_t length, const
 	return length + sizeof(*tlv);
 }
 
+/* Note: <remote> is explicitly allowed to be NULL */
 int make_proxy_line_v2(char *buf, int buf_len, struct server *srv, struct connection *remote)
 {
 	const char pp2_signature[] = PP2_SIGNATURE;
@@ -1060,7 +1062,7 @@ int make_proxy_line_v2(char *buf, int buf_len, struct server *srv, struct connec
 		}
 	}
 
-	if (conn_get_alpn(remote, &value, &value_len)) {
+	if (remote && conn_get_alpn(remote, &value, &value_len)) {
 		if ((buf_len - ret) < sizeof(struct tlv))
 			return 0;
 		ret += make_tlv(&buf[ret], (buf_len - ret), PP2_TYPE_ALPN, value_len, value);