| From | Luis Henriques <> | Subject | [PATCH 3.16.y-ckt 036/130] packet: tpacket_snd(): fix signed/unsigned comparison | Date | Fri, 4 Sep 2015 14:07:04 +0100 |
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3.16.7-ckt17 -stable review patch. If anyone has any objections, please let me know.
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From: Alexander Drozdov <al.drozdov@gmail.com>
commit dbd46ab412b8fb395f2b0ff6f6a7eec9df311550 upstream.
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> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- net/packet/af_packet.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 7dc6a05f09c8..1f2e7d341781 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2284,7 +2284,8 @@ 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
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