From jose.calhariz at tecnico.ulisboa.pt  Tue Jan 10 11:35:47 2017
From: jose.calhariz at tecnico.ulisboa.pt (Jose M Calhariz)
Date: Tue, 10 Jan 2017 19:35:47 +0000
Subject: [Xorp-users] A possible fix for g++ 6
Message-ID: <20170110193547.GA16880@calhariz.com>


Hi,

A user of xorp in Debian have found that in some situations xorp fails
during initialization with a NULL pointer possibly because of new
optimizations in g++ 6.

Is possible to review the patch that he sent me?  The patch is in
attach.

Kind regards
Jose M Calhariz

-- 
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Description: Add some null pointer checks to avoid segfaults.
 When compiled using gcc 6, the initialization process generates segfaults at
 some null pointer dereferences. This problem was probably exposed by the
 behaviour of -fdelete-null-pointer-checks in gcc 6.
Author: Dhionel D?az <ddiaz at cenditel.gob.ve>
Last-Update: 2017-01-04
---
--- a/libxorp/trie.hh
+++ b/libxorp/trie.hh
@@ -623,7 +623,7 @@
      *
      */
     iterator lookup_node(const Key & k) const	{
-	Node *n = _root->find(k);
+	Node *n = (_root) ? _root->find(k) : NULL;
 	return (n && n->k() == k) ? iterator(n) : end();
     }
 
@@ -632,7 +632,7 @@
      * the key passed as parameter.
      */
     iterator search_subtree(const Key &key) const {
-	return iterator(_root->find_subtree(key), key);
+	return (_root) ? iterator(_root->find_subtree(key), key) : end();
     }
 
     /**
@@ -648,7 +648,7 @@
 
 	Key x(key.masked_addr(), key.prefix_len() - 1);
 
-	return iterator(_root->find(x));
+	return (_root) ? iterator(_root->find(x)) : end();
     }
 
     /**
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From greearb at candelatech.com  Tue Jan 10 11:40:47 2017
From: greearb at candelatech.com (Ben Greear)
Date: Tue, 10 Jan 2017 11:40:47 -0800
Subject: [Xorp-users] A possible fix for g++ 6
In-Reply-To: <20170110193547.GA16880@calhariz.com>
References: <20170110193547.GA16880@calhariz.com>
Message-ID: <1edbe413-809f-8349-e0f6-a64ac616214f@candelatech.com>

I would be interested in seeing a backtrace if the user has it
so I could better understand the problem.  Maybe the code should never
actually be trying to call these methods if _root is NULL?

Thanks,
Ben



On 01/10/2017 11:35 AM, Jose M Calhariz wrote:
>
> Hi,
>
> A user of xorp in Debian have found that in some situations xorp fails
> during initialization with a NULL pointer possibly because of new
> optimizations in g++ 6.
>
> Is possible to review the patch that he sent me?  The patch is in
> attach.
>
> Kind regards
> Jose M Calhariz
>
>
>
> _______________________________________________
> Xorp-users mailing list
> Xorp-users at xorp.org
> http://mailman.ICSI.Berkeley.EDU/mailman/listinfo/xorp-users
>


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Ben Greear <greearb at candelatech.com>
Candela Technologies Inc  http://www.candelatech.com