[PATCH net 6/9] batman-adv: fix TX priority extraction for BATADV_FORW_MCAST
From: Simon Wunderlich <sw@simonwunderlich.de>
Date: 2026-08-21 09:48:28
Also in:
batman, stable
Subsystem:
batman advanced, the rest · Maintainers:
Marek Lindner, Simon Wunderlich, Antonio Quartulli, Sven Eckelmann, Linus Torvalds
From: Sven Eckelmann <sven@narfation.org>
batadv_mcast_forw_mode_by_count() pushs the skb->data for BATADV_FORW_MCAST
forwarding via batadv_mcast_forw_mcsend(). But the
batadv_skb_set_priority() expects the ethernet header directly before
(skb->data + offset). With the moved skb->data, just some random data would
be accessed to get the priority data.
Move the batadv_skb_set_priority() before the decision about the handling
multicast packets and potential header modifications.
Cc: stable@vger.kernel.org
Fixes: 90039133221e ("batman-adv: mcast: implement multicast packet generation")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
---
net/batman-adv/mesh-interface.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/net/batman-adv/mesh-interface.c b/net/batman-adv/mesh-interface.c
index 8e55b61dd2a64..e202088cf1fd4 100644
--- a/net/batman-adv/mesh-interface.c
+++ b/net/batman-adv/mesh-interface.c@@ -305,6 +305,8 @@ static netdev_tx_t batadv_interface_tx(struct sk_buff *skb, if (batadv_compare_eth(ethhdr->h_dest, ectp_addr)) goto dropped; + batadv_skb_set_priority(skb, 0); + gw_mode = READ_ONCE(bat_priv->gw.mode); if (is_multicast_ether_addr(ethhdr->h_dest)) { /* if gw mode is off, broadcast every packet */
@@ -338,6 +340,9 @@ static netdev_tx_t batadv_interface_tx(struct sk_buff *skb, send: if (do_bcast && !is_broadcast_ether_addr(ethhdr->h_dest)) { + /* WARNING batadv_mcast_forw_mode might add more headers + * in front of the skb. and might even reallocate the skb + */ forw_mode = batadv_mcast_forw_mode(bat_priv, skb, vid, &mcast_is_routable); switch (forw_mode) {
@@ -355,8 +360,6 @@ static netdev_tx_t batadv_interface_tx(struct sk_buff *skb, } } - batadv_skb_set_priority(skb, 0); - /* ethernet packet should be broadcasted */ if (do_bcast) { primary_if = batadv_primary_if_get_selected(bat_priv);
--
2.47.3