[PATCH net 5/9] batman-adv: tt: prevent TVLV OOB check overflow

From: Sven Eckelmann <[email protected]>

A TT unicast TVLV contains the number of VLANs stored in it. This number is
an u16 and gets multiplied by the size of the struct
batadv_tvlv_tt_vlan_data (8 bytes). The size can therefore overflow the u16
used to store the tt_vlan_len. All additional safety checks to prevent
out-of-bounds access of the TVLV buffer are invalid due to this overflow.

Using size_t prevents this overflow and ensures that the safety checks
compare against the actual buffer requirements.

Cc: [email protected]
Fixes: 7ea7b4a14275 ("batman-adv: make the TT CRC logic VLAN specific")
Signed-off-by: Sven Eckelmann <[email protected]>
Signed-off-by: Simon Wunderlich <[email protected]>
---
 net/batman-adv/translation-table.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
index aae72015645a4..dae5e1d8c0385 100644
--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -4033,7 +4033,8 @@ static int batadv_tt_tvlv_unicast_handler_v1(struct batadv_priv *bat_priv,
 					     u16 tvlv_value_len)
 {
 	struct batadv_tvlv_tt_data *tt_data;
-	u16 tt_vlan_len, tt_num_entries;
+	u16 tt_num_entries;
+	size_t tt_vlan_len;
 	char tt_flag;
 	bool ret;
 
-- 
2.47.3