batman-adv: Fix multicast packet loss with a single WANT_ALL_IPV4/6 flag

[ Upstream commit 74c12c630fe310eb7fcae1b292257d47781fff0a ]

As the kernel doc describes too the code is supposed to skip adding
multicast TT entries if both the WANT_ALL_IPV4 and WANT_ALL_IPV6 flags
are present.

Unfortunately, the current code even skips adding multicast TT entries
if only either the WANT_ALL_IPV4 or WANT_ALL_IPV6 is present.

This could lead to IPv6 multicast packet loss if only an IGMP but not an
MLD querier is present for instance or vice versa.

Fixes: 687937ab3489 ("batman-adv: Add multicast optimization support for bridged setups")
Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/batman-adv/multicast.c b/net/batman-adv/multicast.c
index 13661f43386f09f5661ae1b7444f4c56e63a3b8a..9911cc9dbf6505a42d3c449ec0510bb8a26a7fa5 100644 (file)
--- a/net/batman-adv/multicast.c
+++ b/net/batman-adv/multicast.c
@@ -527,8 +527,8 @@ update:
                bat_priv->mcast.enabled = true;
        }
 
-       return !(mcast_data.flags &
-                (BATADV_MCAST_WANT_ALL_IPV4 | BATADV_MCAST_WANT_ALL_IPV6));
+       return !(mcast_data.flags & BATADV_MCAST_WANT_ALL_IPV4 &&
+                mcast_data.flags & BATADV_MCAST_WANT_ALL_IPV6);
 }
 
 /**