[added to the 4.1 stable tree] netfilter: arp_tables: fix invoking 32bit "iptable -P INPUT ACCEPT" failed in 64bit kernel

[Sasha Levin <Alexander.Levin@microsoft.com>]

From: Hongxu Jia <hongxu.jia@windriver.com>

This patch has been added to the 4.1 stable tree. If you have any
objections, please let us know.

===============

[ Upstream commit 17a49cd549d9dc8707dc9262210166455c612dde ]

Since 09d9686047db ("netfilter: x_tables: do compat validation via
translate_table"), it used compatr structure to assign newinfo
structure.  In translate_compat_table of ip_tables.c and ip6_tables.c,
it used compatr->hook_entry to replace info->hook_entry and
compatr->underflow to replace info->underflow, but not do the same
replacement in arp_tables.c.

It caused invoking 32-bit "arptbale -P INPUT ACCEPT" failed in 64bit
kernel.
--------------------------------------
root@qemux86-64:~# arptables -P INPUT ACCEPT
root@qemux86-64:~# arptables -P INPUT ACCEPT
ERROR: Policy for `INPUT' offset 448 != underflow 0
arptables: Incompatible with this kernel
--------------------------------------

Fixes: 09d9686047db ("netfilter: x_tables: do compat validation via translate_table")
Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 net/ipv4/netfilter/arp_tables.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index ebf5821caefb..7510a851d316 100644
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -1330,8 +1330,8 @@ static int translate_compat_table(struct xt_table_info **pinfo,
 
 	newinfo->number = compatr->num_entries;
 	for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
-		newinfo->hook_entry[i] = info->hook_entry[i];
-		newinfo->underflow[i] = info->underflow[i];
+		newinfo->hook_entry[i] = compatr->hook_entry[i];
+		newinfo->underflow[i] = compatr->underflow[i];
 	}
 	entry1 = newinfo->entries[raw_smp_processor_id()];
 	pos = entry1;
-- 
2.14.1