netdev - [PATCH 12/30] netfilter: x_tables: limit allocation requests for blob rule heads

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Message-Id: <20180312175920.9022-13-pablo@netfilter.org>
Date:   Mon, 12 Mar 2018 18:59:02 +0100
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     netfilter-devel@...r.kernel.org
Cc:     davem@...emloft.net, netdev@...r.kernel.org
Subject: [PATCH 12/30] netfilter: x_tables: limit allocation requests for blob rule heads

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

This is a very conservative limit (134217728 rules), but good
enough to not trigger frequent oom from syzkaller.

Signed-off-by: Florian Westphal <fw@...len.de>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 net/netfilter/x_tables.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index dc68ac49614a..01f8e122e74e 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -894,6 +894,9 @@ EXPORT_SYMBOL(xt_check_entry_offsets);
  */
 unsigned int *xt_alloc_entry_offsets(unsigned int size)
 {
+	if (size > XT_MAX_TABLE_SIZE / sizeof(unsigned int))
+		return NULL;
+
 	return kvmalloc_array(size, sizeof(unsigned int), GFP_KERNEL | __GFP_ZERO);
 
 }
-- 
2.11.0