From 61610c63fa1025468c82be975e7d574e847d00de Mon Sep 17 00:00:00 2001
From: Florian Westphal <fw@strlen.de>
Date: Tue, 30 Aug 2016 00:35:04 -0400
Subject: netfilter: x_tables: check for size overflow

[ Upstream commit d157bd761585605b7882935ffb86286919f62ea1 ]

Ben Hawkes says:
 integer overflow in xt_alloc_table_info, which on 32-bit systems can
 lead to small structure allocation and a copy_from_user based heap
 corruption.

Reported-by: Ben Hawkes <hawkes@google.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/netfilter/x_tables.c | 3 +++
 1 file changed, 3 insertions(+)

(limited to 'net')

diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index c7b7cecb5bd1..2fc6ca9d1286 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -897,6 +897,9 @@ struct xt_table_info *xt_alloc_table_info(unsigned int size)
 	struct xt_table_info *info = NULL;
 	size_t sz = sizeof(*info) + size;
 
+	if (sz < sizeof(*info))
+		return NULL;
+
 	if (sz < sizeof(*info))
 		return NULL;
 
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