Merge tag 'batman-adv-fix-for-davem' of git://git.open-mesh.org/linux-merge

Included change:
- reassign pointers to data after skb reallocation to avoid kernel paging errors

Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 33 insertions, 7 deletions

diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c
index e14531f1ce1c..264de88db320 100644
--- a/net/batman-adv/bridge_loop_avoidance.c
+++ b/net/batman-adv/bridge_loop_avoidance.c
@@ -1529,6 +1529,8 @@ out:
  * in these cases, the skb is further handled by this function and
  * returns 1, otherwise it returns 0 and the caller shall further
  * process the skb.
+ *
+ * This call might reallocate skb data.
  */
 int batadv_bla_tx(struct batadv_priv *bat_priv, struct sk_buff *skb,
                   unsigned short vid)
diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c
index f105219f4a4b..7614af31daff 100644
--- a/net/batman-adv/gateway_client.c
+++ b/net/batman-adv/gateway_client.c
@@ -508,6 +508,7 @@ out:
         return 0;
 }
 
+/* this call might reallocate skb data */
 static bool batadv_is_type_dhcprequest(struct sk_buff *skb, int header_len)
 {
         int ret = false;
@@ -568,6 +569,7 @@ out:
         return ret;
 }
 
+/* this call might reallocate skb data */
 bool batadv_gw_is_dhcp_target(struct sk_buff *skb, unsigned int *header_len)
 {
         struct ethhdr *ethhdr;
@@ -619,6 +621,12 @@ bool batadv_gw_is_dhcp_target(struct sk_buff *skb, unsigned int *header_len)
 
         if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr)))
                 return false;
+
+        /* skb->data might have been reallocated by pskb_may_pull() */
+        ethhdr = (struct ethhdr *)skb->data;
+        if (ntohs(ethhdr->h_proto) == ETH_P_8021Q)
+                ethhdr = (struct ethhdr *)(skb->data + VLAN_HLEN);
+
         udphdr = (struct udphdr *)(skb->data + *header_len);
         *header_len += sizeof(*udphdr);
 
@@ -634,12 +642,14 @@ bool batadv_gw_is_dhcp_target(struct sk_buff *skb, unsigned int *header_len)
         return true;
 }
 
+/* this call might reallocate skb data */
 bool batadv_gw_out_of_range(struct batadv_priv *bat_priv,
-                            struct sk_buff *skb, struct ethhdr *ethhdr)
+                            struct sk_buff *skb)
 {
         struct batadv_neigh_node *neigh_curr = NULL, *neigh_old = NULL;
         struct batadv_orig_node *orig_dst_node = NULL;
         struct batadv_gw_node *curr_gw = NULL;
+        struct ethhdr *ethhdr;
         bool ret, out_of_range = false;
         unsigned int header_len = 0;
         uint8_t curr_tq_avg;
@@ -648,6 +658,7 @@ bool batadv_gw_out_of_range(struct batadv_priv *bat_priv,
         if (!ret)
                 goto out;
 
+        ethhdr = (struct ethhdr *)skb->data;
         orig_dst_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
                                                  ethhdr->h_dest);
         if (!orig_dst_node)
diff --git a/net/batman-adv/gateway_client.h b/net/batman-adv/gateway_client.h
index 039902dca4a6..1037d75da51f 100644
--- a/net/batman-adv/gateway_client.h
+++ b/net/batman-adv/gateway_client.h
@@ -34,7 +34,6 @@ void batadv_gw_node_delete(struct batadv_priv *bat_priv,
 void batadv_gw_node_purge(struct batadv_priv *bat_priv);
 int batadv_gw_client_seq_print_text(struct seq_file *seq, void *offset);
 bool batadv_gw_is_dhcp_target(struct sk_buff *skb, unsigned int *header_len);
-bool batadv_gw_out_of_range(struct batadv_priv *bat_priv,
-                            struct sk_buff *skb, struct ethhdr *ethhdr);
+bool batadv_gw_out_of_range(struct batadv_priv *bat_priv, struct sk_buff *skb);
 
 #endif /* _NET_BATMAN_ADV_GATEWAY_CLIENT_H_ */
diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index 700d0b49742d..0f04e1c302b4 100644
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -180,6 +180,9 @@ static int batadv_interface_tx(struct sk_buff *skb,
         if (batadv_bla_tx(bat_priv, skb, vid))
                 goto dropped;
 
+        /* skb->data might have been reallocated by batadv_bla_tx() */
+        ethhdr = (struct ethhdr *)skb->data;
+
         /* Register the client MAC in the transtable */
         if (!is_multicast_ether_addr(ethhdr->h_source))
                 batadv_tt_local_add(soft_iface, ethhdr->h_source, skb->skb_iif);
@@ -220,6 +223,10 @@ static int batadv_interface_tx(struct sk_buff *skb,
                 default:
                         break;
                 }
+
+                /* reminder: ethhdr might have become unusable from here on
+                 * (batadv_gw_is_dhcp_target() might have reallocated skb data)
+                 */
         }
 
         /* ethernet packet should be broadcasted */
@@ -266,7 +273,7 @@ static int batadv_interface_tx(struct sk_buff *skb,
         /* unicast packet */
         } else {
                 if (atomic_read(&bat_priv->gw_mode) != BATADV_GW_MODE_OFF) {
-                        ret = batadv_gw_out_of_range(bat_priv, skb, ethhdr);
+                        ret = batadv_gw_out_of_range(bat_priv, skb);
                         if (ret)
                                 goto dropped;
                 }
diff --git a/net/batman-adv/unicast.c b/net/batman-adv/unicast.c
index dc8b5d4dd636..688a0419756b 100644
--- a/net/batman-adv/unicast.c
+++ b/net/batman-adv/unicast.c
@@ -326,7 +326,9 @@ static bool batadv_unicast_push_and_fill_skb(struct sk_buff *skb, int hdr_size,
  * @skb: the skb containing the payload to encapsulate
  * @orig_node: the destination node
  *
- * Returns false if the payload could not be encapsulated or true otherwise
+ * Returns false if the payload could not be encapsulated or true otherwise.
+ *
+ * This call might reallocate skb data.
  */
 static bool batadv_unicast_prepare_skb(struct sk_buff *skb,
                                        struct batadv_orig_node *orig_node)
@@ -343,7 +345,9 @@ static bool batadv_unicast_prepare_skb(struct sk_buff *skb,
  * @orig_node: the destination node
  * @packet_subtype: the batman 4addr packet subtype to use
  *
- * Returns false if the payload could not be encapsulated or true otherwise
+ * Returns false if the payload could not be encapsulated or true otherwise.
+ *
+ * This call might reallocate skb data.
  */
 bool batadv_unicast_4addr_prepare_skb(struct batadv_priv *bat_priv,
                                       struct sk_buff *skb,
@@ -401,7 +405,7 @@ int batadv_unicast_generic_send_skb(struct batadv_priv *bat_priv,
         struct batadv_neigh_node *neigh_node;
         int data_len = skb->len;
         int ret = NET_RX_DROP;
-        unsigned int dev_mtu;
+        unsigned int dev_mtu, header_len;
 
         /* get routing information */
         if (is_multicast_ether_addr(ethhdr->h_dest)) {
@@ -429,10 +433,12 @@ find_router:
         switch (packet_type) {
         case BATADV_UNICAST:
                 batadv_unicast_prepare_skb(skb, orig_node);
+                header_len = sizeof(struct batadv_unicast_packet);
                 break;
         case BATADV_UNICAST_4ADDR:
                 batadv_unicast_4addr_prepare_skb(bat_priv, skb, orig_node,
                                                  packet_subtype);
+                header_len = sizeof(struct batadv_unicast_4addr_packet);
                 break;
         default:
                 /* this function supports UNICAST and UNICAST_4ADDR only. It
@@ -441,6 +447,7 @@ find_router:
                 goto out;
         }
 
+        ethhdr = (struct ethhdr *)(skb->data + header_len);
         unicast_packet = (struct batadv_unicast_packet *)skb->data;
 
         /* inform the destination node that we are still missing a correct route