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batman-adv: Do not send uninitialized TT changes

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The number of TT changes can be less than initially expected in
batadv_tt_tvlv_container_update() (changes can be removed by
batadv_tt_local_event() in ADD+DEL sequence between reading
tt_diff_entries_num and actually iterating the change list under lock).

Thus tt_diff_len could be bigger than the actual changes size that need
to be sent. Because batadv_send_my_tt_response sends the whole
packet, uninitialized data can be interpreted as TT changes on other
nodes leading to weird TT global entries on those nodes such as:

 * 00:00:00:00:00:00   -1 [....] (  0) 88:12:4e:ad:7e:ba (179) (0x45845380)
 * 00:00:00:00:78:79 4092 [.W..] (  0) 88:12:4e:ad:7e:3c (145) (0x8ebadb8b)

All of the above also applies to OGM tvlv container buffer's tvlv_len.

Remove the extra allocated space to avoid sending uninitialized TT
changes in batadv_send_my_tt_response() and batadv_v_ogm_send_softif().

Fixes: e1bf0c1409 ("batman-adv: tvlv - convert tt data sent within OGMs")
Signed-off-by: Remi Pommarel <repk@triplefau.lt>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
This commit is contained in:
Remi Pommarel 2024-11-22 16:52:48 +01:00 committed by Simon Wunderlich
parent 40384c840e
commit f2f7358c38
1 changed files with 7 additions and 0 deletions
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7
net/batman-adv/translation-table.c
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@ -948,6 +948,7 @@ static void batadv_tt_tvlv_container_update(struct batadv_priv *bat_priv)
int tt_diff_len, tt_change_len = 0;
int tt_diff_entries_num = 0;
int tt_diff_entries_count = 0;
size_t tt_extra_len = 0;
u16 tvlv_len;
tt_diff_entries_num = atomic_read(&bat_priv->tt.local_changes);
@ -985,6 +986,9 @@ static void batadv_tt_tvlv_container_update(struct batadv_priv *bat_priv)
}
spin_unlock_bh(&bat_priv->tt.changes_list_lock);
tt_extra_len = batadv_tt_len(tt_diff_entries_num -
tt_diff_entries_count);
/* Keep the buffer for possible tt_request */
spin_lock_bh(&bat_priv->tt.last_changeset_lock);
kfree(bat_priv->tt.last_changeset);
@ -993,6 +997,7 @@ static void batadv_tt_tvlv_container_update(struct batadv_priv *bat_priv)
tt_change_len = batadv_tt_len(tt_diff_entries_count);
/* check whether this new OGM has no changes due to size problems */
if (tt_diff_entries_count > 0) {
tt_diff_len -= tt_extra_len;
/* if kmalloc() fails we will reply with the full table
* instead of providing the diff
*/
@ -1005,6 +1010,8 @@ static void batadv_tt_tvlv_container_update(struct batadv_priv *bat_priv)
}
spin_unlock_bh(&bat_priv->tt.last_changeset_lock);
/* Remove extra packet space for OGM */
tvlv_len -= tt_extra_len;
container_register:
batadv_tvlv_container_register(bat_priv, BATADV_TVLV_TT, 1, tt_data,
tvlv_len);