From b2942d59a3cd66a5202eedcd41e751c0d0bd6e5e Mon Sep 17 00:00:00 2001 From: Sven Eckelmann Date: Mon, 31 Dec 2018 22:31:01 +0100 Subject: batman-adv: Force mac header to start of data on xmit commit 9114daa825fc3f335f9bea3313ce667090187280 upstream. The caller of ndo_start_xmit may not already have called skb_reset_mac_header. The returned value of skb_mac_header/eth_hdr therefore can be in the wrong position and even outside the current skbuff. This for example happens when the user binds to the device using a PF_PACKET-SOCK_RAW with enabled qdisc-bypass: int opt = 4; setsockopt(sock, SOL_PACKET, PACKET_QDISC_BYPASS, &opt, sizeof(opt)); Since eth_hdr is used all over the codebase, the batadv_interface_tx function must always take care of resetting it. Fixes: c6c8fea29769 ("net: Add batman-adv meshing protocol") Reported-by: syzbot+9d7405c7faa390e60b4e@syzkaller.appspotmail.com Reported-by: syzbot+7d20bc3f1ddddc0f9079@syzkaller.appspotmail.com Signed-off-by: Sven Eckelmann Signed-off-by: Simon Wunderlich Signed-off-by: Greg Kroah-Hartman --- net/batman-adv/soft-interface.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c index 9f1fe6169bef..5aeb585571ed 100644 --- a/net/batman-adv/soft-interface.c +++ b/net/batman-adv/soft-interface.c @@ -209,6 +209,8 @@ static int batadv_interface_tx(struct sk_buff *skb, soft_iface->trans_start = jiffies; vid = batadv_get_vid(skb, 0); + + skb_reset_mac_header(skb); ethhdr = eth_hdr(skb); switch (ntohs(ethhdr->h_proto)) { -- cgit v1.2.3