| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.1 146/159] packet: tpacket_snd(): fix signed/unsigned comparison | Date | Sat, 26 Sep 2015 13:56:32 -0700 |
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4.1-stable review patch. If anyone has any objections, please let me know.
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From: Alexander Drozdov <al.drozdov@gmail.com>
[ Upstream commit dbd46ab412b8fb395f2b0ff6f6a7eec9df311550 ]
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/packet/af_packet.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2307,7 +2307,8 @@ static int tpacket_snd(struct packet_soc } 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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