[B.A.T.M.A.N.] [PATCH maint v3] batman-adv: Fix multicast packet loss with a single WANT_ALL_IPV4/6 flag

[B.A.T.M.A.N.] [PATCH maint v3] batman-adv: Fix multicast packet loss with a single WANT_ALL_IPV4/6 flag

[Linus Lüssing]

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: 391b59cdb111 ("batman-adv: Add multicast optimization support for bridged setups")
Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
---
v3: Added "Fixes:" line
v2: Fixed typo in last sentence: "non" -> "not"

 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 6eaffe50..15a7b314 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);
 }
 
 /**
-- 
2.11.0

Re: [B.A.T.M.A.N.] [PATCH maint v3] batman-adv: Fix multicast packet loss with a single WANT_ALL_IPV4/6 flag

[Sven Eckelmann]

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On Sonntag, 4. März 2018 13:08:17 CET Linus Lüssing wrote:
> 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: 391b59cdb111 ("batman-adv: Add multicast optimization support for bridged setups")
> Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>

Applied in edba00d56efb [1].

Thanks,
	Sven

[1] https://git.open-mesh.org/batman-adv.git/commit/edba00d56efb1d55cdd40957e010fba80580b5e2

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