linux-kernel - [34-longterm 198/209] x25: Do not reference freed memory.

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Date:	Thu, 14 Apr 2011 13:55:56 -0400
From:	Paul Gortmaker <paul.gortmaker@...driver.com>
To:	stable@...nel.org, linux-kernel@...r.kernel.org
Cc:	stable-review@...nel.org, "David S. Miller" <davem@...emloft.net>,
	Paul Gortmaker <paul.gortmaker@...driver.com>
Subject: [34-longterm 198/209] x25: Do not reference freed memory.

From: David S. Miller <davem@...emloft.net>

  =====================================================================
  | This is a commit scheduled for the next v2.6.34 longterm release. |
  | If you see a problem with using this for longterm, please comment.|
  =====================================================================

commit 96642d42f076101ba98866363d908cab706d156c upstream.

In x25_link_free(), we destroy 'nb' before dereferencing
'nb->dev'.  Don't do this, because 'nb' might be freed
by then.

Reported-by: Randy Dunlap <randy.dunlap@...cle.com>
Tested-by: Randy Dunlap <randy.dunlap@...cle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Paul Gortmaker <paul.gortmaker@...driver.com>
---
 net/x25/x25_link.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/net/x25/x25_link.c b/net/x25/x25_link.c
index b25c646..88048b6 100644
--- a/net/x25/x25_link.c
+++ b/net/x25/x25_link.c
@@ -392,9 +392,12 @@ void __exit x25_link_free(void)
 	write_lock_bh(&x25_neigh_list_lock);
 
 	list_for_each_safe(entry, tmp, &x25_neigh_list) {
+		struct net_device *dev;
+
 		nb = list_entry(entry, struct x25_neigh, node);
+		dev = nb->dev;
 		__x25_remove_neigh(nb);
-		dev_put(nb->dev);
+		dev_put(dev);
 	}
 	write_unlock_bh(&x25_neigh_list_lock);
 }
-- 
1.7.4.4

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