[krbdev.mit.edu #6951] assertion failure when connections fail in service_fds()

[The RT System itself via RT]

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Date: Wed, 31 Aug 2011 14:21:19 -0400
Message-Id: <201108311821.p7VILJGb006504 at blade.bos.redhat.com>
To: krb5-bugs at mit.edu
Subject: assertion failure when connections fail in service_fds()
From: nalin at redhat.com
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>Submitter-Id:	net
>Originator:	
>Organization:
>Confidential:	no
>Synopsis:	assertion failure when connections fail in service_fds()
>Severity:	non-critical
>Priority:	medium
>Category:	krb5-libs
>Class:		sw-bug
>Release:	1.9.1
>Environment:
	
System: Linux blade.bos.redhat.com 2.6.38.8-35.fc15.x86_64 #1 SMP Wed Jul 6 13:58:54 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux
Architecture: x86_64
>Description:
	With the fix for RT#6905 applied and clients building with
	poll(), we're seeing some clients hitting an assertion failure
	when one of the multiple connections that k5_sendto() creates
	fails before a reply is received from another one.
	After a connection's state is marked as FAILED, subsequent
	calls to service_fds() will still attempt to pass that
	connection's descriptor to cm_get_ssflags(), and because the
	descriptor has already been removed from the select_state,
	cm_get_ssflags() will hit an assertion failure.
>How-To-Repeat:
	Configure a client system with a list of KDCs which includes, at
	its front, an address/port combination where there's no KDC
	listening.
>Fix:
	This appears to fix it on my systems:
Index: src/lib/krb5/os/sendto_kdc.c
===================================================================
--- src/lib/krb5/os/sendto_kdc.c	(revision 25119)
+++ src/lib/krb5/os/sendto_kdc.c	(working copy)
@@ -1176,7 +1176,7 @@
         for (state = conns; state != NULL; state = state->next) {
             int ssflags;
 
-            if (state->fd == INVALID_SOCKET)
+            if (state->state == FAILED || state->fd == INVALID_SOCKET)
                 continue;
             ssflags = cm_get_ssflags(seltemp, state->fd);
             if (!ssflags)