* [PATCH net] ipv6: Revert "ipv6: Allow non-gateway ECMP for IPv6"
@ 2018-05-02 19:41 Ido Schimmel
2018-05-02 19:50 ` Eric Dumazet
2018-05-02 20:33 ` David Miller
0 siblings, 2 replies; 3+ messages in thread
From: Ido Schimmel @ 2018-05-02 19:41 UTC (permalink / raw)
To: netdev; +Cc: davem, dsahern, eric.dumazet, Thomas.Winter, mlxsw, Ido Schimmel
This reverts commit edd7ceb78296 ("ipv6: Allow non-gateway ECMP for
IPv6").
Eric reported a division by zero in rt6_multipath_rebalance() which is
caused by above commit that considers identical local routes to be
siblings. The division by zero happens because a nexthop weight is not
set for local routes.
Revert the commit as it does not fix a bug and has side effects.
To reproduce:
# ip -6 address add 2001:db8::1/64 dev dummy0
# ip -6 address add 2001:db8::1/64 dev dummy1
Fixes: edd7ceb78296 ("ipv6: Allow non-gateway ECMP for IPv6")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
---
include/net/ip6_route.h | 3 ++-
net/ipv6/ip6_fib.c | 3 +++
2 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index abceb5864d99..08b132381984 100644
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -68,7 +68,8 @@ static inline bool rt6_need_strict(const struct in6_addr *daddr)
static inline bool rt6_qualify_for_ecmp(const struct rt6_info *rt)
{
- return (rt->rt6i_flags & (RTF_ADDRCONF | RTF_DYNAMIC)) == 0;
+ return (rt->rt6i_flags & (RTF_GATEWAY|RTF_ADDRCONF|RTF_DYNAMIC)) ==
+ RTF_GATEWAY;
}
void ip6_route_input(struct sk_buff *skb);
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 3c97c29d4401..deab2db6692e 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -934,6 +934,9 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct rt6_info *rt,
* list.
* Only static routes (which don't have flag
* RTF_EXPIRES) are used for ECMPv6.
+ *
+ * To avoid long list, we only had siblings if the
+ * route have a gateway.
*/
if (rt_can_ecmp &&
rt6_qualify_for_ecmp(iter))
--
2.14.3
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH net] ipv6: Revert "ipv6: Allow non-gateway ECMP for IPv6"
2018-05-02 19:41 [PATCH net] ipv6: Revert "ipv6: Allow non-gateway ECMP for IPv6" Ido Schimmel
@ 2018-05-02 19:50 ` Eric Dumazet
2018-05-02 20:33 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: Eric Dumazet @ 2018-05-02 19:50 UTC (permalink / raw)
To: Ido Schimmel, netdev; +Cc: davem, dsahern, eric.dumazet, Thomas.Winter, mlxsw
On 05/02/2018 12:41 PM, Ido Schimmel wrote:
> This reverts commit edd7ceb78296 ("ipv6: Allow non-gateway ECMP for
> IPv6").
>
> Eric reported a division by zero in rt6_multipath_rebalance() which is
> caused by above commit that considers identical local routes to be
> siblings. The division by zero happens because a nexthop weight is not
> set for local routes.
>
> Revert the commit as it does not fix a bug and has side effects.
>
> To reproduce:
>
> # ip -6 address add 2001:db8::1/64 dev dummy0
> # ip -6 address add 2001:db8::1/64 dev dummy1
>
> Fixes: edd7ceb78296 ("ipv6: Allow non-gateway ECMP for IPv6")
> Signed-off-by: Ido Schimmel <idosch@mellanox.com>
> Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
> ---
Tested-by: Eric Dumazet <edumazet@google.com>
Thanks for fixing this !
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH net] ipv6: Revert "ipv6: Allow non-gateway ECMP for IPv6"
2018-05-02 19:41 [PATCH net] ipv6: Revert "ipv6: Allow non-gateway ECMP for IPv6" Ido Schimmel
2018-05-02 19:50 ` Eric Dumazet
@ 2018-05-02 20:33 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: David Miller @ 2018-05-02 20:33 UTC (permalink / raw)
To: idosch; +Cc: netdev, dsahern, eric.dumazet, Thomas.Winter, mlxsw
From: Ido Schimmel <idosch@mellanox.com>
Date: Wed, 2 May 2018 22:41:56 +0300
> This reverts commit edd7ceb78296 ("ipv6: Allow non-gateway ECMP for
> IPv6").
>
> Eric reported a division by zero in rt6_multipath_rebalance() which is
> caused by above commit that considers identical local routes to be
> siblings. The division by zero happens because a nexthop weight is not
> set for local routes.
>
> Revert the commit as it does not fix a bug and has side effects.
>
> To reproduce:
>
> # ip -6 address add 2001:db8::1/64 dev dummy0
> # ip -6 address add 2001:db8::1/64 dev dummy1
>
> Fixes: edd7ceb78296 ("ipv6: Allow non-gateway ECMP for IPv6")
> Signed-off-by: Ido Schimmel <idosch@mellanox.com>
> Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Applied, thank you.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2018-05-02 19:41 [PATCH net] ipv6: Revert "ipv6: Allow non-gateway ECMP for IPv6" Ido Schimmel
2018-05-02 19:50 ` Eric Dumazet
2018-05-02 20:33 ` David Miller
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