[PATCH 4.19 038/131] net: Fix the arp error in some cases

Sasha Levin
2020-06-29T20:16:51Z

From: guodeqing <geffrey.guo@huawei.com>

[ Upstream commit 5eea3a63ff4aba6a26002e657a6d21934b7e2b96 ]

ie.,
$ ifconfig eth0 6.6.6.6 netmask 255.255.255.0

$ ip rule add from 6.6.6.6 table 6666

$ ip route add 9.9.9.9 via 6.6.6.6

$ ping -I 6.6.6.6 9.9.9.9
PING 9.9.9.9 (9.9.9.9) from 6.6.6.6 : 56(84) bytes of data.

3 packets transmitted, 0 received, 100% packet loss, time 2079ms

$ arp
Address HWtype HWaddress Flags Mask Iface
6.6.6.6 (incomplete) eth0

The arp request address is error, this is because fib_table_lookup in
fib_check_nh lookup the destnation 9.9.9.9 nexthop, the scope of
the fib result is RT_SCOPE_LINK,the correct scope is RT_SCOPE_HOST.
Here I add a check of whether this is RT_TABLE_MAIN to solve this problem.

Fixes: 3bfd847203c6 ("net: Use passed in table for nexthop lookups")
Signed-off-by: guodeqing <geffrey.guo@huawei.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv4/fib_semantics.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index a8fc4e83cd954..9573cd242b908 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -831,7 +831,7 @@ static int fib_check_nh(struct fib_config *cfg, struct fib_nh *nh,
if (fl4.flowi4_scope < RT_SCOPE_LINK)
fl4.flowi4_scope = RT_SCOPE_LINK;

- if (cfg->fc_table)
+ if (cfg->fc_table && cfg->fc_table != RT_TABLE_MAIN)
tbl = fib_get_table(net, cfg->fc_table);

if (tbl)
--
2.25.1