6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sven Eckelmann commit 6a30a59e2660afd03c975f1b8eae6a2301161197 upstream. batadv_mcast_forw_packet() and batadv_mcast_forw_scrape() is not only called (indirectly) by the unsharing+linearizing batadv_recv_mcast_packet() handler. When it is called (indirectly) 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 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() Cc: stable@vger.kernel.org Reported-by: Sashiko Fixes: 90039133221e ("batman-adv: mcast: implement multicast packet generation") Signed-off-by: Sven Eckelmann Signed-off-by: Greg Kroah-Hartman --- net/batman-adv/multicast_forw.c | 4 ++++ 1 file changed, 4 insertions(+) --- 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 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; }