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batman-adv: tt: avoid empty VLAN responses

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The commit 16116dac23 ("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: 7ea7b4a142 ("batman-adv: make the TT CRC logic VLAN specific")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
This commit is contained in:
Sven Eckelmann 2026-05-02 20:47:34 +02:00
parent 94d2700501
commit fa1bd70494
No known key found for this signature in database
GPG Key ID: 4D0F772BD314F5CB
1 changed files with 17 additions and 3 deletions
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20
net/batman-adv/translation-table.c
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@ -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;