linux-kernel - [PATCH 4.16 18/26] netfilter: x_tables: cap allocations at 512 mbyte

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Message-Id: <20180425103315.583243065@linuxfoundation.org>
Date:   Wed, 25 Apr 2018 12:33:27 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Florian Westphal <fw@...len.de>,
        Pablo Neira Ayuso <pablo@...filter.org>
Subject: [PATCH 4.16 18/26] netfilter: x_tables: cap allocations at 512 mbyte

4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Florian Westphal <fw@...len.de>

commit 19926968ea86a286aa6fbea16ee3f2e7442f10f0 upstream.

Arbitrary limit, however, this still allows huge rulesets
(> 1 million rules).  This helps with automated fuzzer as it prevents
oom-killer invocation.

Signed-off-by: Florian Westphal <fw@...len.de>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 net/netfilter/x_tables.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -40,6 +40,7 @@ MODULE_AUTHOR("Harald Welte <laforge@net
 MODULE_DESCRIPTION("{ip,ip6,arp,eb}_tables backend module");
 
 #define XT_PCPU_BLOCK_SIZE 4096
+#define XT_MAX_TABLE_SIZE	(512 * 1024 * 1024)
 
 struct compat_delta {
 	unsigned int offset; /* offset in kernel */
@@ -1029,7 +1030,7 @@ struct xt_table_info *xt_alloc_table_inf
 	struct xt_table_info *info = NULL;
 	size_t sz = sizeof(*info) + size;
 
-	if (sz < sizeof(*info))
+	if (sz < sizeof(*info) || sz >= XT_MAX_TABLE_SIZE)
 		return NULL;
 
 	/* __GFP_NORETRY is not fully supported by kvmalloc but it should