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Commit 8c137450 authored by Cong Wang's avatar Cong Wang Committed by Greg Kroah-Hartman
Browse files

netfilter: xt_hashlimit: limit the max size of hashtable 



commit 8d0015a7ab76b8b1e89a3e5f5710a6e5103f2dd5 upstream.

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: default avatar <syzbot+adf6c6c2be1c3a718121@syzkaller.appspotmail.com>
Signed-off-by: default avatarCong Wang <xiyou.wangcong@gmail.com>
Reviewed-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 7bd1fc78

net/netfilter/xt_hashlimit.c

+10 −0
Original line number Diff line number Diff line
@@ -735,6 +735,8 @@ hashlimit_mt(const struct sk_buff *skb, struct xt_action_param *par) 
	return hashlimit_mt_common(skb, par, hinfo, &info->cfg, 2);

}



#define HASHLIMIT_MAX_SIZE 1048576



static int hashlimit_mt_check_common(const struct xt_mtchk_param *par,

				     struct xt_hashlimit_htable **hinfo,

				     struct hashlimit_cfg2 *cfg,
@@ -745,6 +747,14 @@ 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;