biff notification can leak descriptor

[Jaroslav Skarvada]

Hi,

biff notification can leak descriptor (reproduced with mailman).
Attached one of possible fixes (also applies to latest postfix
sources)

regards

Jaroslav

diff -up postfix-2.3.3/src/local/biff_notify.c.orig2 postfix-2.3.3/src/local/biff_notify.c
--- postfix-2.3.3/src/local/biff_notify.c.orig2	2005-07-13 22:46:18.000000000 +0200
+++ postfix-2.3.3/src/local/biff_notify.c	2012-07-02 18:17:28.694042972 +0200
@@ -46,6 +46,7 @@
 
 /* Application-specific. */
 
+#include "iostuff.h"
 #include <biff_notify.h>
 
 /* biff_notify - notify recipient via the biff "protocol" */
@@ -81,9 +82,12 @@ void    biff_notify(const char *text, ss
     /*
      * Open a socket, or re-use an existing one.
      */
-    if (sock < 0 && (sock = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
-	msg_warn("socket: %m");
-	return;
+    if (sock < 0) {
+	if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
+	    msg_warn("socket: %m");
+	    return;
+	}
+	close_on_exec(sock, CLOSE_ON_EXEC);
     }
 
     /*