[PATCH 4.9 20/80] ipv6: fix restrict IPV6_ADDRFORM operation

[Greg Kroah-Hartman]

From: John Haxby <john.ha...@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.ha...@oracle.com>
Cc: sta...@vger.kernel.org
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@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
@@ -184,15 +184,14 @@ 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;