Fixed handling of non-null-terminated unix sockets. At least FreeBSD, macOS, NetBSD, and OpenBSD can return unix sockets with non-null-terminated sun_path. Additionally, the address may become non-null-terminated if it does not fit into the buffer provided and was truncated (may happen on macOS, NetBSD, and Solaris, which allow unix socket addresess larger than struct sockaddr_un). As such, ngx_sock_ntop() might overread the sockaddr provided, as it used "%s" format and thus assumed null-terminated string. To fix this, the ngx_strnlen() function was introduced, and it is now used to calculate correct length of sun_path.

--- a/src/core/ngx_inet.c
+++ b/src/core/ngx_inet.c
@@ -241,7 +241,9 @@ ngx_sock_ntop(struct sockaddr *sa, sockl
             p = ngx_snprintf(text, len, "unix:%Z");
 
         } else {
-            p = ngx_snprintf(text, len, "unix:%s%Z", saun->sun_path);
+            n = ngx_strnlen((u_char *) saun->sun_path,
+                            socklen - offsetof(struct sockaddr_un, sun_path));
+            p = ngx_snprintf(text, len, "unix:%*s%Z", n, saun->sun_path);
         }
 
         /* we do not include trailing zero in address length */