ipv4: ipmr: fix NULL pointer deref during unres queue destruction

Fix an oversight in ipmr_destroy_unres() - the net pointer is
unconditionally initialized to NULL, resulting in a NULL pointer
dereference later on.

Fix by adding a net pointer to struct mr_table and using it in
ipmr_destroy_unres().

Signed-off-by: Patrick McHardy <kaber@trash.net>

1 files changed, 5 insertions, 1 deletions

diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 0643fb6d47c4..7d8a2bcecb76 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -71,6 +71,9 @@
 
 struct mr_table {
         struct list_head        list;
+#ifdef CONFIG_NET_NS
+        struct net              *net;
+#endif
         u32                     id;
         struct sock             *mroute_sk;
         struct timer_list       ipmr_expire_timer;
@@ -308,6 +311,7 @@ static struct mr_table *ipmr_new_table(struct net *net, u32 id)
         mrt = kzalloc(sizeof(*mrt), GFP_KERNEL);
         if (mrt == NULL)
                 return NULL;
+        write_pnet(&mrt->net, net);
         mrt->id = id;
 
         /* Forwarding cache */
@@ -580,7 +584,7 @@ static inline void ipmr_cache_free(struct mfc_cache *c)
 
 static void ipmr_destroy_unres(struct mr_table *mrt, struct mfc_cache *c)
 {
-        struct net *net = NULL; //mrt->net;
+        struct net *net = read_pnet(&mrt->net);
         struct sk_buff *skb;
         struct nlmsgerr *e;