The skb_linearize may reallocate the skb. This makes the calculated pointer for ethhdr invalid. But it the pointer is used later to fill in the RR field of the batadv_icmp_packet_rr packet.

Instead re-evaluate eth_hdr after the skb_linearize+skb_cow to fix the pointer and avoid the invalid read.

Fixes: bb69cb678d37 ("batman-adv: generalize batman-adv icmp packet handling") Signed-off-by: Sven Eckelmann sven@narfation.org --- net/batman-adv/routing.c | 1 + 1 file changed, 1 insertion(+)

diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c index 0c0c30e..27e07dd 100644 --- a/net/batman-adv/routing.c +++ b/net/batman-adv/routing.c @@ -374,6 +374,7 @@ int batadv_recv_icmp_packet(struct sk_buff *skb, if (skb_cow(skb, ETH_HLEN) < 0) goto out;

+ ethhdr = eth_hdr(skb); icmph = (struct batadv_icmp_header *)skb->data; icmp_packet_rr = (struct batadv_icmp_packet_rr *)icmph; if (icmp_packet_rr->rr_cur >= BATADV_RR_LEN)