net: Fix header size check for GSO case in recvmsg (af_packet)

Parameter 'len' is size_t type so it will never get negative.

Signed-off-by: Mariusz Kozlowski <mk@lab.zgora.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 1 deletions

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 0856a13cb53d..8298e676f5a0 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1610,9 +1610,11 @@ static int packet_recvmsg(struct kiocb *iocb, struct socket *sock,
 
                 err = -EINVAL;
                 vnet_hdr_len = sizeof(vnet_hdr);
-                if ((len -= vnet_hdr_len) < 0)
+                if (len < vnet_hdr_len)
                         goto out_free;
 
+                len -= vnet_hdr_len;
+
                 if (skb_is_gso(skb)) {
                         struct skb_shared_info *sinfo = skb_shinfo(skb);