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Commit 52cd5750 authored by Ilpo Järvinen's avatar Ilpo Järvinen Committed by David S. Miller
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tcp: fix length used for checksum in a reset 



While looking for some common code I came across difference
in checksum calculation between tcp_v6_send_(reset|ack) I
couldn't explain. I checked both v4 and v6 and found out that
both seem to have the same "feature". I couldn't find anything
in rfc nor anywhere else which would state that md5 option
should be ignored like it was in case of reset so I came to
a conclusion that this is probably a genuine bug. I suspect
that addition of md5 just was fooled by the excessive
copy-paste code in those functions and the reset part was
never tested well enough to find out the problem.

Signed-off-by: default avatarIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 2ca89cea

net/ipv4/tcp_ipv4.c

+1 −1
Original line number Diff line number Diff line
@@ -589,7 +589,7 @@ static void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb) 
#endif

	arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,

				      ip_hdr(skb)->saddr, /* XXX */

				      sizeof(struct tcphdr), IPPROTO_TCP, 0);

				      arg.iov[0].iov_len, IPPROTO_TCP, 0);

	arg.csumoffset = offsetof(struct tcphdr, check) / 2;

	arg.flags = (sk && inet_sk(sk)->transparent) ? IP_REPLY_ARG_NOSRCCHECK : 0;

net/ipv6/tcp_ipv6.c

+2 −2
Original line number Diff line number Diff line
@@ -1012,14 +1012,14 @@ static void tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb) 
	}

#endif



	buff->csum = csum_partial((char *)t1, sizeof(*t1), 0);

	buff->csum = csum_partial((char *)t1, tot_len, 0);



	memset(&fl, 0, sizeof(fl));

	ipv6_addr_copy(&fl.fl6_dst, &ipv6_hdr(skb)->saddr);

	ipv6_addr_copy(&fl.fl6_src, &ipv6_hdr(skb)->daddr);



	t1->check = csum_ipv6_magic(&fl.fl6_src, &fl.fl6_dst,

				    sizeof(*t1), IPPROTO_TCP,

				    tot_len, IPPROTO_TCP,

				    buff->csum);



	fl.proto = IPPROTO_TCP;