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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, John Haxby <john.haxby@oracle.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 5.4 059/168] ipv6: fix restrict IPV6_ADDRFORM operation
Date:   Tue, 28 Apr 2020 20:23:53 +0200
Message-Id: <20200428182239.370140226@linuxfoundation.org>
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From: John Haxby <john.haxby@oracle.com>

[ Upstream commit 82c9ae440857840c56e05d4fb1427ee032531346 ]

Commit b6f6118901d1 ("ipv6: restrict IPV6_ADDRFORM operation") fixed a
problem found by syzbot an unfortunate logic error meant that it
also broke IPV6_ADDRFORM.

Rearrange the checks so that the earlier test is just one of the series
of checks made before moving the socket from IPv6 to IPv4.

Fixes: b6f6118901d1 ("ipv6: restrict IPV6_ADDRFORM operation")
Signed-off-by: John Haxby <john.haxby@oracle.com>
Cc: stable@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/ipv6/ipv6_sockglue.c |   13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -183,15 +183,14 @@ static int do_ipv6_setsockopt(struct soc
 					retv = -EBUSY;
 					break;
 				}
-			} else if (sk->sk_protocol == IPPROTO_TCP) {
-				if (sk->sk_prot != &tcpv6_prot) {
-					retv = -EBUSY;
-					break;
-				}
-				break;
-			} else {
+			}
+			if (sk->sk_protocol == IPPROTO_TCP &&
+			    sk->sk_prot != &tcpv6_prot) {
+				retv = -EBUSY;
 				break;
 			}
+			if (sk->sk_protocol != IPPROTO_TCP)
+				break;
 			if (sk->sk_state != TCP_ESTABLISHED) {
 				retv = -ENOTCONN;
 				break;