tcp: remove redundant checks
tcp_v4_rcv() checks the following before calling tcp_v4_do_rcv():
if (th->doff < sizeof(struct tcphdr) / 4)
goto bad_packet;
if (!pskb_may_pull(skb, th->doff * 4))
goto discard_it;
So following check in tcp_v4_do_rcv() is redundant
and "goto csum_err;" is wrong anyway.
if (skb->len < tcp_hdrlen(skb) || ...)
goto csum_err;
A second check can be removed after no_tcp_socket label for same reason.
Same tests can be removed in tcp_v6_do_rcv()
Note : short tcp frames are not properly accounted in tcpInErrs MIB,
because pskb_may_pull() failure simply drops incoming skb, we might
fix this in a separate patch.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index feb8757..3130c42 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1400,7 +1400,7 @@
return 0;
}
- if (skb->len < tcp_hdrlen(skb) || tcp_checksum_complete(skb))
+ if (tcp_checksum_complete(skb))
goto csum_err;
if (sk->sk_state == TCP_LISTEN) {
@@ -1647,7 +1647,7 @@
if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
goto discard_it;
- if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
+ if (tcp_checksum_complete(skb)) {
csum_error:
TCP_INC_STATS_BH(net, TCP_MIB_CSUMERRORS);
bad_packet: