Re: Patch: Wierd behaviour: postconf -xd proxy_read_maps

[Viktor Dukhovni]

On Wed, Sep 22, 2021 at 10:35:45PM +1000, raf wrote:

> I just encountered a wierd thing (debian-11 stable, postfix-3.5.6-1+b1).

Thanks for the bug report.

>   $ postconf -xdf proxy_read_maps
>   proxy_read_maps = all127.0.0.0/8 a.b.c.d/32 [::1]/128
>    [a:b:c:d::e]/128 [fe80::]/64 hash:/etc/aliases, nis:mail.aliases

The problem is an recursive reuse of a static buffer in the postconf(1)
code (does not affect any other Postfix programs, ...) that expands the
default value of mynetworks, when called recursively from expanding some
other parameter.

Patch below.

-- 
    Viktor.

--- a/src/postconf/postconf_builtin.c
+++ b/src/postconf/postconf_builtin.c
@@ -250,6 +250,7 @@ static const char *pcf_check_mydomainname(void)
 static const char *pcf_mynetworks(void)
 {
     static const char *networks;
+    static VSTRING *local_buf;
     const char *junk;
 
     /*
@@ -258,10 +259,13 @@ static const char *pcf_mynetworks(void)
     if (networks)
        return (networks);
 
+    if (local_buf == 0)
+        local_buf = vstring_alloc(100);
+
     if (var_inet_interfaces == 0) {
        if ((pcf_cmd_mode & PCF_SHOW_DEFS)
            || (junk = mail_conf_lookup_eval(VAR_INET_INTERFACES)) == 0)
-           junk = pcf_expand_parameter_value((VSTRING *) 0, pcf_cmd_mode,
+           junk = pcf_expand_parameter_value(local_buf, pcf_cmd_mode,
                                              DEF_INET_INTERFACES,
                                              (PCF_MASTER_ENT *) 0);
        var_inet_interfaces = mystrdup(junk);
@@ -269,7 +273,7 @@ static const char *pcf_mynetworks(void)
     if (var_mynetworks_style == 0) {
        if ((pcf_cmd_mode & PCF_SHOW_DEFS)
            || (junk = mail_conf_lookup_eval(VAR_MYNETWORKS_STYLE)) == 0)
-           junk = pcf_expand_parameter_value((VSTRING *) 0, pcf_cmd_mode,
+           junk = pcf_expand_parameter_value(local_buf, pcf_cmd_mode,
                                              DEF_MYNETWORKS_STYLE,
                                              (PCF_MASTER_ENT *) 0);
        var_mynetworks_style = mystrdup(junk);
@@ -277,7 +281,7 @@ static const char *pcf_mynetworks(void)
     if (var_inet_protocols == 0) {
        if ((pcf_cmd_mode & PCF_SHOW_DEFS)
            || (junk = mail_conf_lookup_eval(VAR_INET_PROTOCOLS)) == 0)
-           junk = pcf_expand_parameter_value((VSTRING *) 0, pcf_cmd_mode,
+           junk = pcf_expand_parameter_value(local_buf, pcf_cmd_mode,
                                              DEF_INET_PROTOCOLS,
                                              (PCF_MASTER_ENT *) 0);
        var_inet_protocols = mystrdup(junk);