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From schemers@slapshot.stanford.edu  Sun Dec 22 18:51:43 1996
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Date: 22 Dec 1996 15:50:38 -0800
From: Roland Schemers <schemers@stanford.edu>
Sender: schemers@slapshot.stanford.edu
Cc: krb5-bugs@MIT.EDU
In-Reply-To: blizzard@odin.nyser.net's message of 22 Dec 1996 21:35:55 GMT
Subject: krb__get_srvtabname() segfaults if krb5.conf missing
References: <59k9jr$4ka@news.appliedtheory.com>

>Number:         317
>Category:       krb5-libs
>Synopsis:       krb__get_srvtabname() segfaults if krb5.conf missing
>Confidential:   yes
>Severity:       serious
>Priority:       medium
>Responsible:    tlyu
>State:          closed
>Class:          sw-bug
>Submitter-Id:   unknown
>Arrival-Date:   Sun Dec 22 18:52:00 EST 1996
>Last-Modified:  Thu Aug 07 16:32:49 EDT 1997
>Originator:     
>Organization:
>Release:        krb5-1.0
>Environment:
>Description:
The following message is a courtesy copy of an article
that has been posted as well.

blizzard@odin.nyser.net (Christopher Blizzard) writes:
> 
> There seems to be a problem with running the v5 telnetd server without a
> krb5.conf file in place when using a v4 telnet client.  The telnetd server
> will seg fault silently on startup.  To work around this, touch
> /etc/krb5.conf
> 

The bug is in src/lib/krb4/g_cnffile.c:krb__get_srvtabname, line 61:

char *
krb__get_srvtabname(default_srvtabname)
	char *default_srvtabname;
{
	krb5_context context;
	const char* names[3];
	char **full_name = 0, **cpp;
	krb5_error_code retval;
	char *retname;

	krb5_init_context(&context);
	names[0] = "libdefaults";
	names[1] = "krb4_srvtab";
	names[2] = 0;
61:	retval = profile_get_values(context->profile, names, &full_name);
	if (retval == 0 && full_name && full_name[0]) {
		retname = strdup(full_name[0]);
		for (cpp = full_name; *cpp; cpp++) 
			krb5_xfree(*cpp);
		krb5_xfree(full_name);
	} else {
		retname = strdup(default_srvtabname);
	}
	krb5_free_context(context);
	return retname;
}

krb5_int_context is failing and setting context to NULL. Thus the call
to profile_get_values fails. Just need to rearrange things slightly, i.e:

	krb5_init_context(&context);
	names[0] = "libdefaults";
	names[1] = "krb4_srvtab";
	names[2] = 0;
	
	if (context && 
	     (retval = profile_get_values(context->profile, names, &full_name))
		&& retval == 0 && full_name && full_name[0]) {
		retname = strdup(full_name[0]);
		for (cpp = full_name; *cpp; cpp++) 
			krb5_xfree(*cpp);
		krb5_xfree(full_name);
	} else {
		retname = strdup(default_srvtabname);
	}
	if (context) krb5_free_context(context);
	return retname;

roland
>How-To-Repeat:
>Fix:
>Audit-Trail:

Responsible-Changed-From-To: gnats-admin->tlyu
Responsible-Changed-By: tlyu
Responsible-Changed-When: Thu Mar 20 12:38:07 1997
Responsible-Changed-Why:

Refiled

State-Changed-From-To: open-analyzed
State-Changed-By: tlyu
State-Changed-When: Thu Mar 20 12:41:02 1997
State-Changed-Why:

This shouldn't be too hard to deal with.


From: Tom Yu <tlyu@MIT.EDU>
To: schemers@stanford.edu
Cc: krb5-bugs@MIT.EDU
Subject: Re: krb5-libs/317: krb__get_srvtabname() segfaults if krb5.conf missing
Date: Thu, 20 Mar 1997 12:43:01 -0500

 We apologize for not getting back to you sooner, but we have in fact
 received your bug report.
 
 We have not had a chance yet to look at it in detail, but the changes
 you suggest seem resonable.
 
 ---Tom

State-Changed-From-To: analyzed-closed
State-Changed-By: tlyu
State-Changed-When: Thu Aug  7 16:32:24 1997
State-Changed-Why:

Fixed
lib/krb4/g_cnffile.c 1.4

>Unformatted: