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From: Pablo Neira Ayuso <pablo@netfilter.org>
To: netfilter-devel@vger.kernel.org
Cc: davem@davemloft.net, netdev@vger.kernel.org
Subject: [PATCH 2/9] netfilter: xt_hashlimit: limit the max size of hashtable
Date: Tue, 18 Feb 2020 23:20:54 +0100
Message-ID: <20200218222101.635808-3-pablo@netfilter.org> (raw)
In-Reply-To: <20200218222101.635808-1-pablo@netfilter.org>

From: Cong Wang <xiyou.wangcong@gmail.com>

The user-specified hashtable size is unbound, this could
easily lead to an OOM or a hung task as we hold the global
mutex while allocating and initializing the new hashtable.

Add a max value to cap both cfg->size and cfg->max, as
suggested by Florian.

Reported-and-tested-by: syzbot+adf6c6c2be1c3a718121@syzkaller.appspotmail.com
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Reviewed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/xt_hashlimit.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c
index cc475a608f81..7a2c4b8408c4 100644
--- a/net/netfilter/xt_hashlimit.c
+++ b/net/netfilter/xt_hashlimit.c
@@ -837,6 +837,8 @@ hashlimit_mt(const struct sk_buff *skb, struct xt_action_param *par)
 	return hashlimit_mt_common(skb, par, hinfo, &info->cfg, 3);
 }
 
+#define HASHLIMIT_MAX_SIZE 1048576
+
 static int hashlimit_mt_check_common(const struct xt_mtchk_param *par,
 				     struct xt_hashlimit_htable **hinfo,
 				     struct hashlimit_cfg3 *cfg,
@@ -847,6 +849,14 @@ static int hashlimit_mt_check_common(const struct xt_mtchk_param *par,
 
 	if (cfg->gc_interval == 0 || cfg->expire == 0)
 		return -EINVAL;
+	if (cfg->size > HASHLIMIT_MAX_SIZE) {
+		cfg->size = HASHLIMIT_MAX_SIZE;
+		pr_info_ratelimited("size too large, truncated to %u\n", cfg->size);
+	}
+	if (cfg->max > HASHLIMIT_MAX_SIZE) {
+		cfg->max = HASHLIMIT_MAX_SIZE;
+		pr_info_ratelimited("max too large, truncated to %u\n", cfg->max);
+	}
 	if (par->family == NFPROTO_IPV4) {
 		if (cfg->srcmask > 32 || cfg->dstmask > 32)
 			return -EINVAL;
-- 
2.11.0


  parent reply index

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-18 22:20 [PATCH 0/9] Netfilter fixes for net Pablo Neira Ayuso
2020-02-18 22:20 ` [PATCH 1/9] netfilter: xt_hashlimit: reduce hashlimit_mutex scope for htable_put() Pablo Neira Ayuso
2020-02-18 22:20 ` Pablo Neira Ayuso [this message]
2020-02-18 22:20 ` [PATCH 3/9] netfilter: flowtable: skip offload setup if disabled Pablo Neira Ayuso
2020-02-18 22:20 ` [PATCH 4/9] netfilter: conntrack: remove two args from resolve_clash Pablo Neira Ayuso
2020-02-18 22:20 ` [PATCH 5/9] netfilter: conntrack: place confirm-bit setting in a helper Pablo Neira Ayuso
2020-02-18 22:20 ` [PATCH 6/9] netfilter: conntrack: split resolve_clash function Pablo Neira Ayuso
2020-02-18 22:20 ` [PATCH 7/9] netfilter: conntrack: allow insertion of clashing entries Pablo Neira Ayuso
2020-02-18 22:21 ` [PATCH 8/9] netfilter: nft_set_pipapo: Fix mapping table example in comments Pablo Neira Ayuso
2020-02-18 22:21 ` [PATCH 9/9] netfilter: nft_set_pipapo: Don't abuse unlikely() in pipapo_refill() Pablo Neira Ayuso
2020-02-18 23:45 ` [PATCH 0/9] Netfilter fixes for net David Miller

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