bridge: mcast: Fix MLD2 Report IPv6 payload length check

Commit e57f618 ("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: e57f618 ("net: bridge: mcast: fix stale nsrcs pointer in igmp3/mld2 report handling") Acked-by: Nikolay Aleksandrov <[email protected]> Signed-off-by: Linus Lüssing <[email protected]> Signed-off-by: David S. Miller <[email protected]>
fracktal · Jul 7, 2020 · 5fc6266 · 5fc6266
1 parent 394de11
commit 5fc6266
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
@@ -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,