From dbd46ab412b8fb395f2b0ff6f6a7eec9df311550 Mon Sep 17 00:00:00 2001 From: Alexander Drozdov <al.drozdov@gmail.com> Date: Tue, 28 Jul 2015 13:57:01 +0300 Subject: packet: tpacket_snd(): fix signed/unsigned comparison tpacket_fill_skb() can return a negative value (-errno) which is stored in tp_len variable. In that case the following condition will be (but shouldn't be) true: tp_len > dev->mtu + dev->hard_header_len as dev->mtu and dev->hard_header_len are both unsigned. That may lead to just returning an incorrect EMSGSIZE errno to the user. Fixes: 52f1454f629fa ("packet: allow to transmit +4 byte in TX_RING slot for VLAN case") Signed-off-by: Alexander Drozdov <al.drozdov@gmail.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net> --- net/packet/af_packet.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'net') diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index c7c42eb617ef..ed458b315ef4 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2403,7 +2403,8 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg) } tp_len = tpacket_fill_skb(po, skb, ph, dev, size_max, proto, addr, hlen); - if (tp_len > dev->mtu + dev->hard_header_len) { + if (likely(tp_len >= 0) && + tp_len > dev->mtu + dev->hard_header_len) { struct ethhdr *ehdr; /* Earlier code assumed this would be a VLAN pkt, * double-check this now that we have the actual -- cgit v1.2.3