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>

diff --git a/ip/link_gre6.c b/ip/link_gre6.c
index 4d3d4b54210b964d291d2aaca0723726bc1cbb00..447ac5d78ab7b325c7bd1d2e45a373bdbc32e6e3 100644 (file)
--- a/ip/link_gre6.c
+++ b/ip/link_gre6.c
@@ -288,6 +288,7 @@ 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;
                        }
@@ -303,6 +304,7 @@ 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;
                        }