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Commit 7dc68e98 authored by Cong Wang's avatar Cong Wang Committed by Pablo Neira Ayuso
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netfilter: xt_RATEEST: acquire xt_rateest_mutex for hash insert 



rateest_hash is supposed to be protected by xt_rateest_mutex,
and, as suggested by Eric, lookup and insert should be atomic,
so we should acquire the xt_rateest_mutex once for both.

So introduce a non-locking helper for internal use and keep the
locking one for external.

Reported-by: default avatar <syzbot+5cb189720978275e4c75@syzkaller.appspotmail.com>
Fixes: 5859034d ("[NETFILTER]: x_tables: add RATEEST target")
Signed-off-by: default avatarCong Wang <xiyou.wangcong@gmail.com>
Reviewed-by: default avatarFlorian Westphal <fw@strlen.de>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 992cfc7c

net/netfilter/xt_RATEEST.c

+17 −5
Original line number Diff line number Diff line
@@ -39,23 +39,31 @@ static void xt_rateest_hash_insert(struct xt_rateest *est) 
	hlist_add_head(&est->list, &rateest_hash[h]);

}



struct xt_rateest *xt_rateest_lookup(const char *name)

static struct xt_rateest *__xt_rateest_lookup(const char *name)

{

	struct xt_rateest *est;

	unsigned int h;



	h = xt_rateest_hash(name);

	mutex_lock(&xt_rateest_mutex);

	hlist_for_each_entry(est, &rateest_hash[h], list) {

		if (strcmp(est->name, name) == 0) {

			est->refcnt++;

			mutex_unlock(&xt_rateest_mutex);

			return est;

		}

	}

	mutex_unlock(&xt_rateest_mutex);



	return NULL;

}



struct xt_rateest *xt_rateest_lookup(const char *name)

{

	struct xt_rateest *est;



	mutex_lock(&xt_rateest_mutex);

	est = __xt_rateest_lookup(name);

	mutex_unlock(&xt_rateest_mutex);

	return est;

}

EXPORT_SYMBOL_GPL(xt_rateest_lookup);



void xt_rateest_put(struct xt_rateest *est)
@@ -100,8 +108,10 @@ static int xt_rateest_tg_checkentry(const struct xt_tgchk_param *par) 


	net_get_random_once(&jhash_rnd, sizeof(jhash_rnd));



	est = xt_rateest_lookup(info->name);

	mutex_lock(&xt_rateest_mutex);

	est = __xt_rateest_lookup(info->name);

	if (est) {

		mutex_unlock(&xt_rateest_mutex);

		/*

		 * If estimator parameters are specified, they must match the

		 * existing estimator.
@@ -139,11 +149,13 @@ static int xt_rateest_tg_checkentry(const struct xt_tgchk_param *par) 


	info->est = est;

	xt_rateest_hash_insert(est);

	mutex_unlock(&xt_rateest_mutex);

	return 0;



err2:

	kfree(est);

err1:

	mutex_unlock(&xt_rateest_mutex);

	return ret;

}