From: Stefano Brivio <sbrivio@redhat.com>
Date: Wed, 24 Oct 2018 14:37:21 +0200
Subject: ipv6/ndisc: Preserve IPv6 control buffer if protocol error handlers
are called
Git-commit: ee1abcf689353f36d9322231b4320926096bdee0
Patch-mainline: v4.20-rc1
References: networking-stable-18_11_02
Commit a61bbcf28a8c ("[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 f2776ff04722 ("[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 b94f1c0904da ("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: b94f1c0904da ("ipv6: Use icmpv6_notify() to propagate redirect, instead of rt6_redirect().")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
net/ipv6/ndisc.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index a25cfdd47c89..659ecf4e4b3c 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -1732,10 +1732,9 @@ int ndisc_rcv(struct sk_buff *skb)
return 0;
}
- memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
-
switch (msg->icmph.icmp6_type) {
case NDISC_NEIGHBOUR_SOLICITATION:
+ memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
ndisc_recv_ns(skb);
break;
--
2.19.1