Re: Zmailer denial-of-service attack

[Matti Aarnio <mea@utu.fi>]

>   The following message will cause the Zmailer 2.99.26 (probably 
> earlier versions too) router to dump core.
> -----------------------------
...
>   This kind of message is easy to create via a mail client like Eudora, 
> and if you send a few copies, it will quickly kill off all routers, 
> stopping all mail processing.  I'd recommend that everyone test that 
> their router works properly by put the above message into a file, mode 
> 0600, and move it into the $POSTOFFICE/router directory.
> 
>   The problem is in ~/router/rfc822.c in the prctladdr() function.  The 
> problem appears to be a double pointer dereference.  
> The following patch removes the extra "*".

	The patch is incorrect (dreadfull words..) here is the correct way:
	(manually edited into your patch)

*** rfc822.c.orig	Mon Feb 12 02:24:42 1996
--- rfc822.c	Mon Feb 12 02:25:03 1996
***************
*** 1942,1948 ****
  			} else
  				x = l;
  			if (x != NULL) {
! 				if (*x->string == '\0')
  					putc('-', fp);
  				else
  					fprintf(fp, "%s", x->string);
--- 1942,1948 ----
  			} else
  				x = l;
  			if (x != NULL) {
! 				if (x->string == NULL || *x->string == '\0')
  					putc('-', fp);
  				else
  					fprintf(fp, "%s", x->string);


-----------------------

	However it should not be needed in the first place..
	This means that on quad of   channel/host/addr/attrs
	the host entry was not a string at all, rather some
	LISPish list..

> Tom

	/Matti Aarnio