From 74c12c630fe310eb7fcae1b292257d47781fff0a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Linus=20L=C3=BCssing?= <linus.luessing@c0d3.blue>
Date: Sun, 4 Mar 2018 13:08:17 +0100
Subject: [PATCH] batman-adv: Fix multicast packet loss with a single WANT_ALL_IPV4/6 flag
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Git-commit: 74c12c630fe310eb7fcae1b292257d47781fff0a
Patch-mainline: v4.16-rc7
References: bsc#1051510

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>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 net/batman-adv/multicast.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/batman-adv/multicast.c b/net/batman-adv/multicast.c
index cbdeb47ec3f6..d70640135e3a 100644
--- a/net/batman-adv/multicast.c
+++ b/net/batman-adv/multicast.c
@@ -543,8 +543,8 @@ static bool batadv_mcast_mla_tvlv_update(struct batadv_priv *bat_priv)
 		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);
 }
 
 /**
-- 
2.18.0