batman-adv: Fix incorrect offset in batadv_tt_tvlv_ogm_handler_v1()

Since commit 4436df478860 ("batman-adv: Add flex array to struct
batadv_tvlv_tt_data"), the introduction of batadv_tvlv_tt_data's flex
array member in batadv_tt_tvlv_ogm_handler_v1() put tt_changes at
invalid offset. Those TT changes are supposed to be filled from the end
of batadv_tvlv_tt_data structure (including vlan_data flexible array),
but only the flex array size is taken into account missing completely
the size of the fixed part of the structure itself.

Fix the tt_change offset computation by using struct_size() instead of
flex_array_size() so both flex array member and its container structure
sizes are taken into account.

Cc: stable@vger.kernel.org
Fixes: 4436df478860 ("batman-adv: Add flex array to struct batadv_tvlv_tt_data")
Signed-off-by: Remi Pommarel <repk@triplefau.lt>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>

diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
index 760d51fdbdf6026ce8cf110de8a629d2badaa576..7d5de4cbb814fbc3ae6e34cff97cd668b7f79112 100644 (file)
--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -3959,23 +3959,21 @@ static void batadv_tt_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
        struct batadv_tvlv_tt_change *tt_change;
        struct batadv_tvlv_tt_data *tt_data;
        u16 num_entries, num_vlan;
-       size_t flex_size;
+       size_t tt_data_sz;
 
        if (tvlv_value_len < sizeof(*tt_data))
                return;
 
        tt_data = tvlv_value;
-       tvlv_value_len -= sizeof(*tt_data);
-
        num_vlan = ntohs(tt_data->num_vlan);
 
-       flex_size = flex_array_size(tt_data, vlan_data, num_vlan);
-       if (tvlv_value_len < flex_size)
+       tt_data_sz = struct_size(tt_data, vlan_data, num_vlan);
+       if (tvlv_value_len < tt_data_sz)
                return;
 
        tt_change = (struct batadv_tvlv_tt_change *)((void *)tt_data
-                                                    + flex_size);
-       tvlv_value_len -= flex_size;
+                                                    + tt_data_sz);
+       tvlv_value_len -= tt_data_sz;
 
        num_entries = batadv_tt_entries(tvlv_value_len);