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 <[email protected]> Acked-by: Eric Dumazet <[email protected]> Signed-off-by: David S. Miller <[email protected]>
mrcsosa · Jul 15, 2010 · 91a72a7 · 91a72a7
1 parent 87fd308
commit 91a72a7
Showing 1 changed file with 4 additions and 1 deletion.
diff --git 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) {