netdev - [PATCH 2/3] batman-adv: Remove uninitialized data in full table TT response

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Message-Id: <20241210135024.39068-3-sw@simonwunderlich.de>
Date: Tue, 10 Dec 2024 14:50:23 +0100
From: Simon Wunderlich <sw@...onwunderlich.de>
To: davem@...emloft.net,
	kuba@...nel.org
Cc: netdev@...r.kernel.org,
	b.a.t.m.a.n@...ts.open-mesh.org,
	Remi Pommarel <repk@...plefau.lt>,
	Sven Eckelmann <sven@...fation.org>,
	Simon Wunderlich <sw@...onwunderlich.de>
Subject: [PATCH 2/3] batman-adv: Remove uninitialized data in full table TT response

From: Remi Pommarel <repk@...plefau.lt>

The number of entries filled by batadv_tt_tvlv_generate() can be less
than initially expected in batadv_tt_prepare_tvlv_{global,local}_data()
(changes can be removed by batadv_tt_local_event() in ADD+DEL sequence
in the meantime as the lock held during the whole tvlv global/local data
generation).

Thus tvlv_len could be bigger than the actual TT entry size that need
to be sent so full table TT_RESPONSE could hold invalid TT entries such
as below.

 * 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)

Remove the extra allocated space to avoid sending uninitialized entries
for full table TT_RESPONSE in both batadv_send_other_tt_response() and
batadv_send_my_tt_response().

Fixes: 7ea7b4a14275 ("batman-adv: make the TT CRC logic VLAN specific")
Signed-off-by: Remi Pommarel <repk@...plefau.lt>
Signed-off-by: Sven Eckelmann <sven@...fation.org>
Signed-off-by: Simon Wunderlich <sw@...onwunderlich.de>
---
 net/batman-adv/translation-table.c | 37 ++++++++++++++++++------------
 1 file changed, 22 insertions(+), 15 deletions(-)

diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
index 996d1f01171a..f5201738628c 100644
--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -2712,14 +2712,16 @@ static bool batadv_tt_global_valid(const void *entry_ptr,
  *
  * Fills the tvlv buff with the tt entries from the specified hash. If valid_cb
  * is not provided then this becomes a no-op.
+ *
+ * Return: Remaining unused length in tvlv_buff.
  */
-static void batadv_tt_tvlv_generate(struct batadv_priv *bat_priv,
-				    struct batadv_hashtable *hash,
-				    void *tvlv_buff, u16 tt_len,
-				    bool (*valid_cb)(const void *,
-						     const void *,
-						     u8 *flags),
-				    void *cb_data)
+static u16 batadv_tt_tvlv_generate(struct batadv_priv *bat_priv,
+				   struct batadv_hashtable *hash,
+				   void *tvlv_buff, u16 tt_len,
+				   bool (*valid_cb)(const void *,
+						    const void *,
+						    u8 *flags),
+				   void *cb_data)
 {
 	struct batadv_tt_common_entry *tt_common_entry;
 	struct batadv_tvlv_tt_change *tt_change;
@@ -2733,7 +2735,7 @@ static void batadv_tt_tvlv_generate(struct batadv_priv *bat_priv,
 	tt_change = tvlv_buff;
 
 	if (!valid_cb)
-		return;
+		return tt_len;
 
 	rcu_read_lock();
 	for (i = 0; i < hash->size; i++) {
@@ -2759,6 +2761,8 @@ static void batadv_tt_tvlv_generate(struct batadv_priv *bat_priv,
 		}
 	}
 	rcu_read_unlock();
+
+	return batadv_tt_len(tt_tot - tt_num_entries);
 }
 
 /**
@@ -3029,10 +3033,11 @@ static bool batadv_send_other_tt_response(struct batadv_priv *bat_priv,
 			goto out;
 
 		/* fill the rest of the tvlv with the real TT entries */
-		batadv_tt_tvlv_generate(bat_priv, bat_priv->tt.global_hash,
-					tt_change, tt_len,
-					batadv_tt_global_valid,
-					req_dst_orig_node);
+		tvlv_len -= batadv_tt_tvlv_generate(bat_priv,
+						    bat_priv->tt.global_hash,
+						    tt_change, tt_len,
+						    batadv_tt_global_valid,
+						    req_dst_orig_node);
 	}
 
 	/* Don't send the response, if larger than fragmented packet. */
@@ -3156,9 +3161,11 @@ static bool batadv_send_my_tt_response(struct batadv_priv *bat_priv,
 			goto out;
 
 		/* fill the rest of the tvlv with the real TT entries */
-		batadv_tt_tvlv_generate(bat_priv, bat_priv->tt.local_hash,
-					tt_change, tt_len,
-					batadv_tt_local_valid, NULL);
+		tvlv_len -= batadv_tt_tvlv_generate(bat_priv,
+						    bat_priv->tt.local_hash,
+						    tt_change, tt_len,
+						    batadv_tt_local_valid,
+						    NULL);
 	}
 
 	tvlv_tt_data->flags = BATADV_TT_RESPONSE;
-- 
2.39.5