batman-adv: tt: avoid empty VLAN responses

The commit 16116dac2339 ("batman-adv: prevent TT request storms by not
sending inconsistent TT TLVLs") added checks to the local (direct) TT
response code. But the response can also be done indirectly by another node
using the global TT state. To avoid such inconsistency states reported in
the original fix, also avoid sending empty VLANs for replies from the
global TT state.

Cc: stable@kernel.org
Fixes: 7ea7b4a14275 ("batman-adv: make the TT CRC logic VLAN specific")
Signed-off-by: Sven Eckelmann <sven@narfation.org>

diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
index f009cbf8a276844a8a69d7cf1b448c1167b1505f..2259b241e0b56b1433f0dc77d6d1961fb7f17ed9 100644 (file)
--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -797,24 +797,26 @@ batadv_tt_prepare_tvlv_global_data(struct batadv_orig_node *orig_node,
                                   s32 *tt_len)
 {
        u16 num_vlan = 0;
-       u16 num_entries = 0;
        u16 tvlv_len = 0;
        unsigned int change_offset;
        struct batadv_tvlv_tt_vlan_data *tt_vlan;
        struct batadv_orig_node_vlan *vlan;
+       u16 total_entries = 0;
        u8 *tt_change_ptr;
+       int vlan_entries;
 
        spin_lock_bh(&orig_node->vlan_list_lock);
        hlist_for_each_entry(vlan, &orig_node->vlan_list, list) {
+               vlan_entries = atomic_read(&vlan->tt.num_entries);
+               total_entries += vlan_entries;
                num_vlan++;
-               num_entries += atomic_read(&vlan->tt.num_entries);
        }
 
        change_offset = struct_size(*tt_data, vlan_data, num_vlan);
 
        /* if tt_len is negative, allocate the space needed by the full table */
        if (*tt_len < 0)
-               *tt_len = batadv_tt_len(num_entries);
+               *tt_len = batadv_tt_len(total_entries);
 
        if (change_offset > U16_MAX || *tt_len > U16_MAX - change_offset) {
                *tt_len = 0;
@@ -835,14 +837,26 @@ batadv_tt_prepare_tvlv_global_data(struct batadv_orig_node *orig_node,
        (*tt_data)->num_vlan = htons(num_vlan);
 
        tt_vlan = (*tt_data)->vlan_data;
+       num_vlan = 0;
        hlist_for_each_entry(vlan, &orig_node->vlan_list, list) {
+               vlan_entries = atomic_read(&vlan->tt.num_entries);
+               if (vlan_entries < 1)
+                       continue;
+
                tt_vlan->vid = htons(vlan->vid);
                tt_vlan->crc = htonl(vlan->tt.crc);
                tt_vlan->reserved = 0;
 
                tt_vlan++;
+               num_vlan++;
        }
 
+       /* recalculate in case number of VLANs reduced */
+       change_offset = struct_size(*tt_data, vlan_data, num_vlan);
+       tvlv_len = *tt_len + change_offset;
+
+       (*tt_data)->num_vlan = htons(num_vlan);
+
        tt_change_ptr = (u8 *)*tt_data + change_offset;
        *tt_change = (struct batadv_tvlv_tt_change *)tt_change_ptr;