4.4-stable review patch. If anyone has any objections, please let me know.
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From: Sven Eckelmann sven@narfation.org
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 sven@narfation.org Signed-off-by: Simon Wunderlich sw@simonwunderlich.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/batman-adv/soft-interface.c | 2 ++ 1 file changed, 2 insertions(+)
--- 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
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)) {