linux-kernel - [PATCH v2 net] tcp: md5: incorrect tcp_header

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Date:   Wed, 20 Apr 2022 17:50:26 -0700
From:   fruggeri@...sta.com (Francesco Ruggeri)
To:     pabeni@...hat.com, kuba@...nel.org, dsahern@...nel.org,
        yoshfuji@...ux-ipv6.org, davem@...emloft.net, edumazet@...gle.com,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        fruggeri@...sta.com
Subject: [PATCH v2 net] tcp: md5: incorrect tcp_header_len for incoming
 connections

In tcp_create_openreq_child we adjust tcp_header_len for md5 using the
remote address in newsk. But that address is still 0 in newsk at this
point, and it is only set later by the callers (tcp_v[46]_syn_recv_sock).
Use the address from the request socket instead.

v2: Added "Fixes:" line.

Fixes: cfb6eeb4c860 ("[TCP]: MD5 Signature Option (RFC2385) support.")
Signed-off-by: Francesco Ruggeri <fruggeri@...sta.com>
---
 net/ipv4/tcp_minisocks.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 6366df7aaf2a..6854bb1fb32b 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -531,7 +531,7 @@ struct sock *tcp_create_openreq_child(const struct sock *sk,
 	newtp->tsoffset = treq->ts_off;
 #ifdef CONFIG_TCP_MD5SIG
 	newtp->md5sig_info = NULL;	/*XXX*/
-	if (newtp->af_specific->md5_lookup(sk, newsk))
+	if (treq->af_specific->req_md5_lookup(sk, req_to_sk(req)))
 		newtp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED;
 #endif
 	if (skb->len >= TCP_MSS_DEFAULT + newtp->tcp_header_len)
-- 
2.28.0