netdev - [PATCH net-next-2.6] net/core: neighbour update Oops

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Date:	Tue, 13 Jul 2010 08:23:16 -0700 (PDT)
From:	Doug Kehn <rdkehn@...oo.com>
To:	davem@...emloft.net
Cc:	netdev@...r.kernel.org, eric.dumazet@...il.com
Subject: [PATCH net-next-2.6] net/core: neighbour update Oops

When configuring DMVPN (GRE + openNHRP) and a GRE remote
address is configured a kernel Oops is observed.  The
obserseved Oops is caused by a NULL header_ops pointer
(neigh->dev->header_ops) in neigh_update_hhs() when

void (*update)(struct hh_cache*, const struct net_device*, const unsigned char *)
= neigh->dev->header_ops->cache_update;

is executed.  The dev associated with the NULL header_ops is
the GRE interface.  This patch guards against the
possibility that header_ops is NULL.

This Oops was first observed in kernel version 2.6.26.8.

Signed-off-by: Doug Kehn <rdkehn@...oo.com>
---
 net/core/neighbour.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 6ba1c0e..a4e0a74 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -949,7 +949,10 @@ static void neigh_update_hhs(struct neighbour *neigh)
 {
 	struct hh_cache *hh;
 	void (*update)(struct hh_cache*, const struct net_device*, const unsigned char *)
-		= neigh->dev->header_ops->cache_update;
+		= NULL;
+
+	if (neigh->dev->header_ops)
+		update = neigh->dev->header_ops->cache_update;
 
 	if (update) {
 		for (hh = neigh->hh; hh; hh = hh->hh_next) {
-- 
1.7.0.4



      
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