From: Florian Westphal <fw@strlen.de>
Date: Thu, 10 Mar 2016 01:56:23 +0100
Subject: netfilter: x_tables: check for size overflow
Origin: https://git.kernel.org/cgit/linux/kernel/git/pablo/nf-next.git/commit?id=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>
---
 net/netfilter/x_tables.c | 3 +++
 1 file changed, 3 insertions(+)

--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -658,6 +658,9 @@ struct xt_table_info *xt_alloc_table_inf
 	struct xt_table_info *info = NULL;
 	size_t sz = sizeof(*info) + size;
 
+	if (sz < sizeof(*info))
+		return NULL;
+
 	/* Pedantry: prevent them from hitting BUG() in vmalloc.c --RR */
 	if ((SMP_ALIGN(size) >> PAGE_SHIFT) + 2 > totalram_pages)
 		return NULL;
