Here are various batman-adv bugfixes:

- fix tp_meter counter underflow during shutdown, by Luxiao Xu
 
  - fix tp_meter tp_vars reference leak in receiver shutdown,
    by Sven Eckelmann
 
  - fix various translation table integer handling issues,
    by Sven Eckelmann (3 patches)
 
  - fix various translation table counter issues,
    by Sven Eckelmann (3 patches)
 
  - fix fragment reassembly length accounting, by Ruide Cao
 
  - clear current gateway during teardown, by Ruijie Li
 
  - handle forward allocation error in DAT, by Sven Eckelmann
 
  - tp_meter: avoid use of uninitialized sender variables in tp_meter,
    by Sven Eckelmann
 
  - disallow unicast fragment in fragment, by Sven Eckelmann
 
  - directly shut down tp_meter timer on cleanup, by Sven Eckelmann
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Merge tag 'batadv-net-pullrequest-20260515' of https://git.open-mesh.org/batadv

Simon Wunderlich says:

====================
Here are various batman-adv bugfixes:

 - fix tp_meter counter underflow during shutdown, by Luxiao Xu

 - fix tp_meter tp_vars reference leak in receiver shutdown,
   by Sven Eckelmann

 - fix various translation table integer handling issues,
   by Sven Eckelmann (3 patches)

 - fix various translation table counter issues,
   by Sven Eckelmann (3 patches)

 - fix fragment reassembly length accounting, by Ruide Cao

 - clear current gateway during teardown, by Ruijie Li

 - handle forward allocation error in DAT, by Sven Eckelmann

 - tp_meter: avoid use of uninitialized sender variables in tp_meter,
   by Sven Eckelmann

 - disallow unicast fragment in fragment, by Sven Eckelmann

 - directly shut down tp_meter timer on cleanup, by Sven Eckelmann

* tag 'batadv-net-pullrequest-20260515' of https://git.open-mesh.org/batadv:
  batman-adv: tp_meter: directly shut down timer on cleanup
  batman-adv: frag: disallow unicast fragment in fragment
  batman-adv: tp_meter: avoid use of uninit sender vars
  batman-adv: dat: handle forward allocation error
  batman-adv: clear current gateway during teardown
  batman-adv: fix fragment reassembly length accounting
  batman-adv: tt: prevent TVLV entry number overflow
  batman-adv: tt: avoid empty VLAN responses
  batman-adv: tt: fix TOCTOU race for reported vlans
  batman-adv: tt: fix negative last_changeset_len
  batman-adv: tt: fix negative tt_buff_len
  batman-adv: tt: reject oversized local TVLV buffers
  batman-adv: tp_meter: fix tp_vars reference leak in receiver shutdown
  batman-adv: fix tp_meter counter underflow during shutdown
====================

Link: https://patch.msgid.link/20260515095540.325586-1-sw@simonwunderlich.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/batman-adv/distributed-arp-table.c

@@ -696,6 +696,9 @@ static bool batadv_dat_forward_data(struct batadv_priv *bat_priv,
 			goto free_orig;
 
 		tmp_skb = pskb_copy_for_clone(skb, GFP_ATOMIC);
+		if (!tmp_skb)
+			goto free_neigh;
+
 		if (!batadv_send_skb_prepare_unicast_4addr(bat_priv, tmp_skb,
 							   cand[i].orig_node,
 							   packet_subtype)) {

net/batman-adv/fragmentation.c

@@ -17,6 +17,7 @@
 #include <linux/lockdep.h>
 #include <linux/minmax.h>
 #include <linux/netdevice.h>
+#include <linux/overflow.h>
 #include <linux/skbuff.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
@@ -80,9 +81,9 @@ void batadv_frag_purge_orig(struct batadv_orig_node *orig_node,
  *
  * Return: the maximum size of payload that can be fragmented.
  */
-static int batadv_frag_size_limit(void)
+static size_t batadv_frag_size_limit(void)
 {
-	int limit = BATADV_FRAG_MAX_FRAG_SIZE;
+	size_t limit = BATADV_FRAG_MAX_FRAG_SIZE;
 
 	limit -= sizeof(struct batadv_frag_packet);
 	limit *= BATADV_FRAG_MAX_FRAGMENTS;
@@ -143,7 +144,9 @@ static bool batadv_frag_insert_packet(struct batadv_orig_node *orig_node,
 	struct batadv_frag_packet *frag_packet;
 	u8 bucket;
 	u16 seqno, hdr_size = sizeof(struct batadv_frag_packet);
+	bool overflow = false;
 	bool ret = false;
+	size_t data_len;
 
 	/* Linearize packet to avoid linearizing 16 packets in a row when doing
 	 * the later merge. Non-linear merge should be added to remove this
@@ -153,6 +156,7 @@ static bool batadv_frag_insert_packet(struct batadv_orig_node *orig_node,
 		goto err;
 
 	frag_packet = (struct batadv_frag_packet *)skb->data;
+	data_len = skb->len - hdr_size;
 	seqno = ntohs(frag_packet->seqno);
 	bucket = seqno % BATADV_FRAG_BUFFER_COUNT;
 
@@ -171,7 +175,7 @@ static bool batadv_frag_insert_packet(struct batadv_orig_node *orig_node,
 	spin_lock_bh(&chain->lock);
 	if (batadv_frag_init_chain(chain, seqno)) {
 		hlist_add_head(&frag_entry_new->list, &chain->fragment_list);
-		chain->size = skb->len - hdr_size;
+		chain->size = data_len;
 		chain->timestamp = jiffies;
 		chain->total_size = ntohs(frag_packet->total_size);
 		ret = true;
@@ -188,7 +192,11 @@ static bool batadv_frag_insert_packet(struct batadv_orig_node *orig_node,
 		if (frag_entry_curr->no < frag_entry_new->no) {
 			hlist_add_before(&frag_entry_new->list,
 					 &frag_entry_curr->list);
-			chain->size += skb->len - hdr_size;
+
+			if (check_add_overflow(chain->size, data_len,
+					       &chain->size))
+				overflow = true;
+
 			chain->timestamp = jiffies;
 			ret = true;
 			goto out;
@@ -201,13 +209,16 @@ static bool batadv_frag_insert_packet(struct batadv_orig_node *orig_node,
 	/* Reached the end of the list, so insert after 'frag_entry_last'. */
 	if (likely(frag_entry_last)) {
 		hlist_add_behind(&frag_entry_new->list, &frag_entry_last->list);
-		chain->size += skb->len - hdr_size;
+
+		if (check_add_overflow(chain->size, data_len, &chain->size))
+			overflow = true;
+
 		chain->timestamp = jiffies;
 		ret = true;
 	}
 
 out:
-	if (chain->size > batadv_frag_size_limit() ||
+	if (overflow || chain->size > batadv_frag_size_limit() ||
 	    chain->total_size != ntohs(frag_packet->total_size) ||
 	    chain->total_size > batadv_frag_size_limit()) {
 		/* Clear chain if total size of either the list or the packet
@@ -293,6 +304,31 @@ batadv_frag_merge_packets(struct hlist_head *chain)
 	return skb_out;
 }
 
+/**
+ * batadv_skb_is_frag() - check if newly merged skb is gain a unicast packet
+ * @skb: newly merged skb
+ *
+ * Return: if newly skb is of type BATADV_UNICAST_FRAG
+ */
+static bool batadv_skb_is_frag(struct sk_buff *skb)
+{
+	struct batadv_ogm_packet *batadv_ogm_packet;
+
+	/* packet should hold at least type and version */
+	if (unlikely(!pskb_may_pull(skb, 2)))
+		return false;
+
+	batadv_ogm_packet = (struct batadv_ogm_packet *)skb->data;
+
+	if (batadv_ogm_packet->version != BATADV_COMPAT_VERSION)
+		return false;
+
+	if (batadv_ogm_packet->packet_type != BATADV_UNICAST_FRAG)
+		return false;
+
+	return true;
+}
+
 /**
  * batadv_frag_skb_buffer() - buffer fragment for later merge
  * @skb: skb to buffer
@@ -326,6 +362,16 @@ bool batadv_frag_skb_buffer(struct sk_buff **skb,
 	if (!skb_out)
 		goto out_err;
 
+	/* fragment in fragment is not allowed. otherwise it is possible
+	 * to exhaust the stack when receiving a matryoshka-style
+	 * "fragments in a fragment packet"
+	 */
+	if (batadv_skb_is_frag(skb_out)) {
+		kfree_skb(skb_out);
+		skb_out = NULL;
+		goto out_err;
+	}
+
 out:
 	ret = true;
 out_err:

net/batman-adv/gateway_client.c

@@ -478,10 +478,14 @@ void batadv_gw_node_delete(struct batadv_priv *bat_priv,
  */
 void batadv_gw_node_free(struct batadv_priv *bat_priv)
 {
+	struct batadv_gw_node *curr_gw;
 	struct batadv_gw_node *gw_node;
 	struct hlist_node *node_tmp;
 
 	spin_lock_bh(&bat_priv->gw.list_lock);
+	curr_gw = rcu_replace_pointer(bat_priv->gw.curr_gw, NULL, true);
+	batadv_gw_node_put(curr_gw);
+
 	hlist_for_each_entry_safe(gw_node, node_tmp,
 				  &bat_priv->gw.gateway_list, list) {
 		hlist_del_init_rcu(&gw_node->list);

net/batman-adv/tp_meter.c

@@ -8,6 +8,7 @@
 #include "main.h"
 
 #include <linux/atomic.h>
+#include <linux/bug.h>
 #include <linux/build_bug.h>
 #include <linux/byteorder/generic.h>
 #include <linux/cache.h>
@@ -400,13 +401,7 @@ static void batadv_tp_sender_cleanup(struct batadv_tp_vars *tp_vars)
 	batadv_tp_list_detach(tp_vars);
 
 	/* kill the timer and remove its reference */
-	timer_delete_sync(&tp_vars->timer);
-	/* the worker might have rearmed itself therefore we kill it again. Note
-	 * that if the worker should run again before invoking the following
-	 * timer_delete(), it would not re-arm itself once again because the status
-	 * is OFF now
-	 */
-	timer_delete(&tp_vars->timer);
+	timer_shutdown_sync(&tp_vars->timer);
 	batadv_tp_vars_put(tp_vars);
 }
 
@@ -451,7 +446,7 @@ static void batadv_tp_sender_end(struct batadv_priv *bat_priv,
 static void batadv_tp_sender_shutdown(struct batadv_tp_vars *tp_vars,
 				      enum batadv_tp_meter_reason reason)
 {
-	if (!atomic_dec_and_test(&tp_vars->sending))
+	if (atomic_xchg(&tp_vars->sending, 0) != 1)
 		return;
 
 	tp_vars->reason = reason;
@@ -663,6 +658,9 @@ static void batadv_tp_recv_ack(struct batadv_priv *bat_priv,
 	if (unlikely(!tp_vars))
 		return;
 
+	if (unlikely(tp_vars->role != BATADV_TP_SENDER))
+		goto out;
+
 	if (unlikely(atomic_read(&tp_vars->sending) == 0))
 		goto out;
 
@@ -885,7 +883,7 @@ static int batadv_tp_send(void *arg)
 				   "Meter: %s() cannot send packets (%d)\n",
 				   __func__, err);
 			/* ensure nobody else tries to stop the thread now */
-			if (atomic_dec_and_test(&tp_vars->sending))
+			if (atomic_xchg(&tp_vars->sending, 0) == 1)
 				tp_vars->reason = err;
 			break;
 		}
@@ -1100,12 +1098,16 @@ void batadv_tp_stop(struct batadv_priv *bat_priv, const u8 *dst,
 	if (!tp_vars) {
 		batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
 			   "Meter: trying to interrupt an already over connection\n");
-		goto out;
+		goto out_put_orig_node;
 	}
 
+	if (unlikely(tp_vars->role != BATADV_TP_SENDER))
+		goto out_put_tp_vars;
+
 	batadv_tp_sender_shutdown(tp_vars, return_value);
+out_put_tp_vars:
 	batadv_tp_vars_put(tp_vars);
-out:
+out_put_orig_node:
 	batadv_orig_node_put(orig_node);
 }
 
@@ -1156,6 +1158,9 @@ static void batadv_tp_receiver_shutdown(struct timer_list *t)
 	spin_unlock_bh(&tp_vars->unacked_lock);
 
 	/* drop reference of timer */
+	if (WARN_ON(atomic_xchg(&tp_vars->receiving, 0) != 1))
+		return;
+
 	batadv_tp_vars_put(tp_vars);
 }
 
@@ -1374,6 +1379,7 @@ batadv_tp_init_recv(struct batadv_priv *bat_priv,
 
 	ether_addr_copy(tp_vars->other_end, icmp->orig);
 	tp_vars->role = BATADV_TP_RECEIVER;
+	atomic_set(&tp_vars->receiving, 1);
 	memcpy(tp_vars->session, icmp->session, sizeof(tp_vars->session));
 	tp_vars->last_recv = BATADV_TP_FIRST_SEQ;
 	tp_vars->bat_priv = bat_priv;
@@ -1546,8 +1552,12 @@ void batadv_tp_stop_all(struct batadv_priv *bat_priv)
 			break;
 		case BATADV_TP_RECEIVER:
 			batadv_tp_list_detach(tp_var);
-			if (timer_shutdown_sync(&tp_var->timer))
-				batadv_tp_vars_put(tp_var);
+			timer_shutdown_sync(&tp_var->timer);
+
+			if (atomic_xchg(&tp_var->receiving, 0) != 1)
+				break;
+
+			batadv_tp_vars_put(tp_var);
 			break;
 		}
 

net/batman-adv/translation-table.c

@@ -797,24 +797,33 @@ 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;
+	u16 sum_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);
+
+		if (check_add_overflow(vlan_entries, total_entries, &sum_entries)) {
+			*tt_len = 0;
+			goto out;
+		}
+
+		total_entries = sum_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 +844,26 @@ 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;
 
@@ -877,21 +898,25 @@ batadv_tt_prepare_tvlv_local_data(struct batadv_priv *bat_priv,
 {
 	struct batadv_tvlv_tt_vlan_data *tt_vlan;
 	struct batadv_meshif_vlan *vlan;
+	size_t change_offset;
 	u16 num_vlan = 0;
-	u16 vlan_entries = 0;
 	u16 total_entries = 0;
 	u16 tvlv_len;
 	u8 *tt_change_ptr;
-	int change_offset;
+	int vlan_entries;
+	u16 sum_entries;
 
 	spin_lock_bh(&bat_priv->meshif_vlan_list_lock);
 	hlist_for_each_entry(vlan, &bat_priv->meshif_vlan_list, list) {
 		vlan_entries = atomic_read(&vlan->tt.num_entries);
-		if (vlan_entries < 1)
-			continue;
 
+		if (check_add_overflow(vlan_entries, total_entries, &sum_entries)) {
+			tvlv_len = 0;
+			goto out;
+		}
+
+		total_entries = sum_entries;
 		num_vlan++;
-		total_entries += vlan_entries;
 	}
 
 	change_offset = struct_size(*tt_data, vlan_data, num_vlan);
@@ -900,8 +925,10 @@ batadv_tt_prepare_tvlv_local_data(struct batadv_priv *bat_priv,
 	if (*tt_len < 0)
 		*tt_len = batadv_tt_len(total_entries);
 
-	tvlv_len = *tt_len;
-	tvlv_len += change_offset;
+	if (check_add_overflow(*tt_len, change_offset, &tvlv_len)) {
+		tvlv_len = 0;
+		goto out;
+	}
 
 	*tt_data = kmalloc(tvlv_len, GFP_ATOMIC);
 	if (!*tt_data) {
@@ -914,6 +941,7 @@ batadv_tt_prepare_tvlv_local_data(struct batadv_priv *bat_priv,
 	(*tt_data)->num_vlan = htons(num_vlan);
 
 	tt_vlan = (*tt_data)->vlan_data;
+	num_vlan = 0;
 	hlist_for_each_entry(vlan, &bat_priv->meshif_vlan_list, list) {
 		vlan_entries = atomic_read(&vlan->tt.num_entries);
 		if (vlan_entries < 1)
@@ -924,8 +952,15 @@ batadv_tt_prepare_tvlv_local_data(struct batadv_priv *bat_priv,
 		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;
 

net/batman-adv/types.h

@@ -301,7 +301,7 @@ struct batadv_frag_table_entry {
 	u16 seqno;
 
 	/** @size: accumulated size of packets in list */
-	u16 size;
+	size_t size;
 
 	/** @total_size: expected size of the assembled packet */
 	u16 total_size;
@@ -452,7 +452,7 @@ struct batadv_orig_node {
 	 * @tt_buff_len: length of the last tt changeset this node received
 	 *  from the orig node
 	 */
-	s16 tt_buff_len;
+	u16 tt_buff_len;
 
 	/** @tt_buff_lock: lock that protects tt_buff and tt_buff_len */
 	spinlock_t tt_buff_lock;
@@ -993,7 +993,7 @@ struct batadv_priv_tt {
 	 * @last_changeset_len: length of last tt changeset this host has
 	 *  generated
 	 */
-	s16 last_changeset_len;
+	u16 last_changeset_len;
 
 	/**
 	 * @last_changeset_lock: lock protecting last_changeset &
@@ -1323,6 +1323,9 @@ struct batadv_tp_vars {
 	/** @sending: sending binary semaphore: 1 if sending, 0 is not */
 	atomic_t sending;
 
+	/** @receiving: receiving binary semaphore: 1 if receiving, 0 is not */
+	atomic_t receiving;
+
 	/** @reason: reason for a stopped session */
 	enum batadv_tp_meter_reason reason;