Commit 2647feb6 authored by Stefano Brivio's avatar Stefano Brivio Committed by Greg Kroah-Hartman

ipv6/ndisc: Preserve IPv6 control buffer if protocol error handlers are called

[ Upstream commit ee1abcf689353f36d9322231b4320926096bdee0 ]

Commit a61bbcf2 ("[NET]: Store skb->timestamp as offset to a base
timestamp") introduces a neighbour control buffer and zeroes it out in
ndisc_rcv(), as ndisc_recv_ns() uses it.

Commit f2776ff0 ("[IPV6]: Fix address/interface handling in UDP and
DCCP, according to the scoping architecture.") introduces the usage of the
IPv6 control buffer in protocol error handlers (e.g. inet6_iif() in
present-day __udp6_lib_err()).

Now, with commit b94f1c09 ("ipv6: Use icmpv6_notify() to propagate
redirect, instead of rt6_redirect()."), we call protocol error handlers
from ndisc_redirect_rcv(), after the control buffer is already stolen and
some parts are already zeroed out. This implies that inet6_iif() on this
path will always return zero.

This gives unexpected results on UDP socket lookup in __udp6_lib_err(), as
we might actually need to match sockets for a given interface.

Instead of always claiming the control buffer in ndisc_rcv(), do that only
when needed.

Fixes: b94f1c09 ("ipv6: Use icmpv6_notify() to propagate redirect, instead of rt6_redirect().")
Signed-off-by: default avatarStefano Brivio <>
Reviewed-by: default avatarSabrina Dubroca <>
Signed-off-by: default avatarDavid S. Miller <>
Signed-off-by: default avatarGreg Kroah-Hartman <>
parent ef1cb6b0
......@@ -1649,10 +1649,9 @@ int ndisc_rcv(struct sk_buff *skb)
return 0;
memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
switch (msg->icmph.icmp6_type) {
memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
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