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bridge: mcast: Fix MLD2 Report IPv6 payload length check

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Commit e57f61858b ("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: e57f61858b ("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>
This commit is contained in:
Linus Lüssing 2020-07-05 21:10:17 +02:00 committed by David S. Miller
parent 394de110a7
commit 5fc6266af7
1 changed files with 1 additions and 1 deletions
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2
net/bridge/br_multicast.c
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@ -1007,7 +1007,7 @@ static int br_ip6_multicast_mld2_report(struct net_bridge *br,
nsrcs_offset = len + offsetof(struct mld2_grec, grec_nsrcs); nsrcs_offset = len + offsetof(struct mld2_grec, grec_nsrcs);
if (skb_transport_offset(skb) + ipv6_transport_len(skb) < if (skb_transport_offset(skb) + ipv6_transport_len(skb) <
nsrcs_offset + sizeof(_nsrcs)) nsrcs_offset + sizeof(__nsrcs))
return -EINVAL; return -EINVAL;
_nsrcs = skb_header_pointer(skb, nsrcs_offset, _nsrcs = skb_header_pointer(skb, nsrcs_offset,