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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 1/9] netfilter: xt_hashlimit: reduce hashlimit_mutex scope for htable_put()
Date: Tue, 18 Feb 2020 23:20:53 +0100
Message-ID: <20200218222101.635808-2-pablo@netfilter.org> (raw)
In-Reply-To: <20200218222101.635808-1-pablo@netfilter.org>

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

It is unnecessary to hold hashlimit_mutex for htable_destroy()
as it is already removed from the global hashtable and its
refcount is already zero.

Also, switch hinfo->use to refcount_t so that we don't have
to hold the mutex until it reaches zero in htable_put().

Reported-and-tested-by: syzbot+adf6c6c2be1c3a718121@syzkaller.appspotmail.com
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/xt_hashlimit.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c
index bccd47cd7190..cc475a608f81 100644
--- a/net/netfilter/xt_hashlimit.c
+++ b/net/netfilter/xt_hashlimit.c
@@ -36,6 +36,7 @@
 #include <linux/netfilter_ipv6/ip6_tables.h>
 #include <linux/mutex.h>
 #include <linux/kernel.h>
+#include <linux/refcount.h>
 #include <uapi/linux/netfilter/xt_hashlimit.h>
 
 #define XT_HASHLIMIT_ALL (XT_HASHLIMIT_HASH_DIP | XT_HASHLIMIT_HASH_DPT | \
@@ -114,7 +115,7 @@ struct dsthash_ent {
 
 struct xt_hashlimit_htable {
 	struct hlist_node node;		/* global list of all htables */
-	int use;
+	refcount_t use;
 	u_int8_t family;
 	bool rnd_initialized;
 
@@ -315,7 +316,7 @@ static int htable_create(struct net *net, struct hashlimit_cfg3 *cfg,
 	for (i = 0; i < hinfo->cfg.size; i++)
 		INIT_HLIST_HEAD(&hinfo->hash[i]);
 
-	hinfo->use = 1;
+	refcount_set(&hinfo->use, 1);
 	hinfo->count = 0;
 	hinfo->family = family;
 	hinfo->rnd_initialized = false;
@@ -420,7 +421,7 @@ static struct xt_hashlimit_htable *htable_find_get(struct net *net,
 	hlist_for_each_entry(hinfo, &hashlimit_net->htables, node) {
 		if (!strcmp(name, hinfo->name) &&
 		    hinfo->family == family) {
-			hinfo->use++;
+			refcount_inc(&hinfo->use);
 			return hinfo;
 		}
 	}
@@ -429,12 +430,11 @@ static struct xt_hashlimit_htable *htable_find_get(struct net *net,
 
 static void htable_put(struct xt_hashlimit_htable *hinfo)
 {
-	mutex_lock(&hashlimit_mutex);
-	if (--hinfo->use == 0) {
+	if (refcount_dec_and_mutex_lock(&hinfo->use, &hashlimit_mutex)) {
 		hlist_del(&hinfo->node);
+		mutex_unlock(&hashlimit_mutex);
 		htable_destroy(hinfo);
 	}
-	mutex_unlock(&hashlimit_mutex);
 }
 
 /* The algorithm used is the Simple Token Bucket Filter (TBF)
-- 
2.11.0


  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 ` Pablo Neira Ayuso [this message]
2020-02-18 22:20 ` [PATCH 2/9] netfilter: xt_hashlimit: limit the max size of hashtable Pablo Neira Ayuso
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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