From d6a328b00aeff188172d3951786e2cef8bb69c29 Mon Sep 17 00:00:00 2001
From: Florian Westphal <fw@strlen.de>
Date: Tue, 27 Feb 2018 19:42:33 +0100
Subject: [PATCH 07/19] netfilter: x_tables: add counters allocation wrapper
Git-commit: c84ca954ac9fa67a6ce27f91f01e4451c74fd8f6 
Patch-mainline: v4.17-rc1 
References: git-fixes

allows to have size checks in a single spot.
This is supposed to reduce oom situations when fuzz-testing xtables.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: Denis Kirjanov <dkirjanov@suse.com>
---
 include/linux/netfilter/x_tables.h |  1 +
 net/ipv4/netfilter/arp_tables.c    |  2 +-
 net/ipv4/netfilter/ip_tables.c     |  2 +-
 net/ipv6/netfilter/ip6_tables.c    |  2 +-
 net/netfilter/x_tables.c           | 15 +++++++++++++++
 5 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h
index b3044c2c62cb..2120cd63db3c 100644
--- a/include/linux/netfilter/x_tables.h
+++ b/include/linux/netfilter/x_tables.h
@@ -298,6 +298,7 @@ int xt_data_to_user(void __user *dst, const void *src,
 
 void *xt_copy_counters_from_user(const void __user *user, unsigned int len,
 				 struct xt_counters_info *info, bool compat);
+struct xt_counters *xt_counters_alloc(unsigned int counters);
 
 struct xt_table *xt_register_table(struct net *net,
 				   const struct xt_table *table,
diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index 11726a2e2c9f..769220f4ec98 100644
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -882,7 +882,7 @@ static int __do_replace(struct net *net, const char *name,
 	struct arpt_entry *iter;
 
 	ret = 0;
-	counters = vzalloc(num_counters * sizeof(struct xt_counters));
+	counters = xt_counters_alloc(num_counters);
 	if (!counters) {
 		ret = -ENOMEM;
 		goto out;
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index 7bf9d034112f..0966c3b60e59 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -1049,7 +1049,7 @@ __do_replace(struct net *net, const char *name, unsigned int valid_hooks,
 	struct ipt_entry *iter;
 
 	ret = 0;
-	counters = vzalloc(num_counters * sizeof(struct xt_counters));
+	counters = xt_counters_alloc(num_counters);
 	if (!counters) {
 		ret = -ENOMEM;
 		goto out;
diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index f2b3b5879536..2ec20a59d6cb 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -1069,7 +1069,7 @@ __do_replace(struct net *net, const char *name, unsigned int valid_hooks,
 	struct ip6t_entry *iter;
 
 	ret = 0;
-	counters = vzalloc(num_counters * sizeof(struct xt_counters));
+	counters = xt_counters_alloc(num_counters);
 	if (!counters) {
 		ret = -ENOMEM;
 		goto out;
diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index 5cb719a877cd..8586eef34303 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -1159,6 +1159,21 @@ static int xt_jumpstack_alloc(struct xt_table_info *i)
 	return 0;
 }
 
+struct xt_counters *xt_counters_alloc(unsigned int counters)
+{
+	struct xt_counters *mem;
+
+	if (counters == 0 || counters > INT_MAX / sizeof(*mem))
+		return NULL;
+
+	counters *= sizeof(*mem);
+	if (counters > XT_MAX_TABLE_SIZE)
+		return NULL;
+
+	return vzalloc(counters);
+}
+EXPORT_SYMBOL(xt_counters_alloc);
+
 struct xt_table_info *
 xt_replace_table(struct xt_table *table,
 	      unsigned int num_counters,
-- 
2.16.4