Commit aef7a9e2 authored Jul 05, 2020 by Linus Lüssing Committed by Greg Kroah-Hartman Jul 22, 2020

bridge: mcast: Fix MLD2 Report IPv6 payload length check



[ Upstream commit 5fc6266af7b427243da24f3443a50cd4584aac06 ]

Commit e57f6185 ("net: bridge: mcast: fix stale nsrcs pointer in
igmp3/mld2 report handling") introduced a bug in the IPv6 header payload
length check which would potentially lead to rejecting a valid MLD2 Report:

The check needs to take into account the 2 bytes for the "Number of
Sources" field in the "Multicast Address Record" before reading it.
And not the size of a pointer to this field.

Fixes: e57f6185 ("net: bridge: mcast: fix stale nsrcs pointer in igmp3/mld2 report handling")
Acked-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 587ccf09

net/bridge/br_multicast.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1007,7 +1007,7 @@ static int br_ip6_multicast_mld2_report(struct net_bridge *br,
		nsrcs_offset = len + offsetof(struct mld2_grec, grec_nsrcs);

		if (skb_transport_offset(skb) + ipv6_transport_len(skb) <
		nsrcs_offset + sizeof(_nsrcs))
		nsrcs_offset + sizeof(__nsrcs))
		return -EINVAL;

		_nsrcs = skb_header_pointer(skb, nsrcs_offset,