[PATCH 4.19 055/131] ipv6: fix restrict IPV6_ADDRFORM operation

[Greg Kroah-Hartman]

From: John Haxby <john.haxby@xxxxxxxxxx>

[ 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@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 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
@@ -185,15 +185,14 @@ 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;