batadv_mcast_forw_packet() and batadv_mcast_forw_packet() is not only called by the unsharing+linearizing batadv_recv_mcast_packet() handler. When it is called by batadv_mcast_forw_mcsend() then it will be unshared but not linearized. The SKB_LINEAR_ASSERT() can therefore cause a fatal BUG().
The linearization should happen during the expansion of the head because the call chain because the scrape function can be hit already during the initial batadv_mcast_forw_mode() selection code: * batadv_interface_tx * batadv_mcast_forw_mode * batadv_mcast_forw_mode_by_count() * batadv_mcast_forw_push() -> calls batadv_mcast_forw_expand_head() before everything else * batadv_mcast_forw_push_tvlvs() * batadv_mcast_forw_push_dests() * batadv_mcast_forw_push_adjust_padding() * batadv_mcast_forw_scrape() Reported-by: Sashiko <[email protected]> Fixes: 8ed36122d709 ("batman-adv: mcast: implement multicast packet reception and forwarding") Signed-off-by: Sven Eckelmann <[email protected]> --- net/batman-adv/multicast_forw.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/batman-adv/multicast_forw.c b/net/batman-adv/multicast_forw.c index c5b8e2e3..d8374ef5 100644 --- a/net/batman-adv/multicast_forw.c +++ b/net/batman-adv/multicast_forw.c @@ -1103,6 +1103,10 @@ static int batadv_mcast_forw_expand_head(struct batadv_priv *bat_priv, if (skb_cow(skb, hdr_size) < 0) return -ENOMEM; + /* batadv_mcast_forw_scrape() + batadv_mcast_forw_packet() require linearized skb */ + if (skb_linearize(skb) < 0) + return -ENOMEM; + return 0; } -- 2.47.3
