From 449517f7769dde4905564ce17e126bfd4e1f7147 Mon Sep 17 00:00:00 2001
From: Phil Sutter <psutter@redhat.com>
Date: Fri, 6 Oct 2017 17:27:09 +0200
Subject: [PATCH] link_gre6: Fix for changing tclass/flowlabel

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1487486
Upstream Status: iproute2.git commit e7fefb3214b5a

commit e7fefb3214b5a1ed030cab9df513560c503a9851
Author: Phil Sutter <phil@nwl.cc>
Date:   Fri Sep 1 16:08:08 2017 +0200

    link_gre6: Fix for changing tclass/flowlabel

    When trying to change tclass or flowlabel of a GREv6 tunnel which has
    the respective value set already, the code accidentally bitwise OR'ed
    the old and the new value, leading to unexpected results. Fix this by
    clearing the relevant bits of flowinfo variable prior to assigning the
    new value.

    Fixes: af89576d7a8c4 ("iproute2: GRE over IPv6 tunnel support.")
    Signed-off-by: Phil Sutter <phil@nwl.cc>
---
 ip/link_gre6.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/ip/link_gre6.c b/ip/link_gre6.c
index 76416b2..fe3ab64 100644
--- a/ip/link_gre6.c
+++ b/ip/link_gre6.c
@@ -282,6 +282,7 @@ get_failed:
 			else {
 				if (get_u8(&uval, *argv, 16))
 					invarg("invalid TClass", *argv);
+				flowinfo &= ~IP6_FLOWINFO_TCLASS;
 				flowinfo |= htonl((__u32)uval << 20) & IP6_FLOWINFO_TCLASS;
 				flags &= ~IP6_TNL_F_USE_ORIG_TCLASS;
 			}
@@ -297,6 +298,7 @@ get_failed:
 					invarg("invalid Flowlabel", *argv);
 				if (uval > 0xFFFFF)
 					invarg("invalid Flowlabel", *argv);
+				flowinfo &= ~IP6_FLOWINFO_FLOWLABEL;
 				flowinfo |= htonl(uval) & IP6_FLOWINFO_FLOWLABEL;
 				flags &= ~IP6_TNL_F_USE_ORIG_FLOWLABEL;
 			}
-- 
1.8.3.1