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Date:      Tue, 30 Jun 2009 22:33:12 +0300
From:      Mikolaj Golub <to.my.trociny@gmail.com>
To:        bug-followup@FreeBSD.org
Cc:        freebsd-net@FreeBSD.org, Alexander Motin <mav@FreeBSD.org>, Sergei Cherveni <sergei.cherveni@gmail.com>
Subject:   Re: kern/134557: [netgraph] [hang] 7.2 with mpd5.3 hanging up - ng_pptp problem
Message-ID:  <86ocs5zfd3.fsf@kopusha.onet>
In-Reply-To: <200906101720.n5AHK3pr036971@freefall.freebsd.org> (Roar Pettersen's message of "Wed\, 10 Jun 2009 17\:20\:03 GMT")
References:  <200906101720.n5AHK3pr036971@freefall.freebsd.org>

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--=-=-=

Unfortunately, the problem was introduced by this commit :-)

----------

Author: 	mav
Date: 	Sat Jan 31 12:48:09 2009 UTC (4 months, 4 weeks ago)
Log Message: 	

MFC rev. 187495

Check for infinite recursion possible on some broken PPTP/L2TP/... VPN setups.
Mark packets with mbuf_tag on first interface passage and drop on second.

PR:		ports/129625, ports/125303

----------

If a packet goes through two or more ng interfaces, "while" loop in the tag
checking code can run infinitely. The attached patch should fix this.

-- 
Mikolaj Golub


--=-=-=
Content-Type: text/x-diff
Content-Disposition: attachment; filename=ng_iface.c.patch

--- netgraph/ng_iface.c.orig	2009-06-30 21:47:54.000000000 +0300
+++ netgraph/ng_iface.c	2009-06-30 21:49:29.000000000 +0300
@@ -365,7 +365,8 @@
 	}
 
 	/* Protect from deadly infinite recursion. */
-	while ((mtag = m_tag_locate(m, MTAG_NGIF, MTAG_NGIF_CALLED, NULL))) {
+	mtag = NULL;
+	while ((mtag = m_tag_locate(m, MTAG_NGIF, MTAG_NGIF_CALLED, mtag))) {
 		if (*(struct ifnet **)(mtag + 1) == ifp) {
 			log(LOG_NOTICE, "Loop detected on %s\n", ifp->if_xname);
 			m_freem(m);

--=-=-=--



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