diff -ur postgresql-14.0.orig/src/bin/pg_upgrade/option.c postgresql-14.0/src/bin/pg_upgrade/option.c
--- postgresql-14.0.orig/src/bin/pg_upgrade/option.c	2021-11-01 14:54:18.782057697 +0100
+++ postgresql-14.0/src/bin/pg_upgrade/option.c	2021-11-01 14:54:35.649100699 +0100
@@ -476,8 +476,14 @@
 	 */
 	if (GET_MAJOR_VERSION(cluster->major_version) >= 901)
 	{
-		if (!live_check)
+		if (!live_check) {
 			cluster->sockdir = user_opts.socketdir;
+#ifndef UNIX_PATH_MAX
+#define UNIX_PATH_MAX 108
+#endif
+			if (strlen(cluster->sockdir) >= UNIX_PATH_MAX - sizeof(".s.PGSQL.50432"))
+				strcpy(cluster->sockdir, "/tmp"); /* fall back to tmp */
+		}
 		else
 		{
 			/*
diff -ur postgresql-14.0.orig/src/include/pg_config_manual.h postgresql-14.0/src/include/pg_config_manual.h
--- postgresql-14.0.orig/src/include/pg_config_manual.h	2021-11-01 14:54:18.575057170 +0100
+++ postgresql-14.0/src/include/pg_config_manual.h	2021-11-01 14:54:35.767101001 +0100
@@ -207,7 +207,7 @@
  * support them yet.
  */
 #ifndef WIN32
-#define DEFAULT_PGSOCKET_DIR  "/tmp"
+#define DEFAULT_PGSOCKET_DIR  "/var/run/postgresql"
 #else
 #define DEFAULT_PGSOCKET_DIR ""
 #endif