tcp: remove redundant checks (12e25e10) · Commits · 戴 / test

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>

net/ipv4/tcp_ipv4.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -1400,7 +1400,7 @@ int tcp_v4_do_rcv(struct sock sk, struct sk_buff skb)
		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 @@ no_tcp_socket:
		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:

net/ipv6/tcp_ipv6.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -1250,7 +1250,7 @@ static int tcp_v6_do_rcv(struct sock sk, struct sk_buff skb)
		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) {
		@@ -1442,7 +1442,7 @@ no_tcp_socket:

		tcp_v6_fill_cb(skb, hdr, th);

		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:

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