netfilter: xt_hashlimit: limit the max size of hashtable (8d0015a7) · Commits · 戴 / test

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 −0

Original line number	Diff line number	Diff line
		@@ -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;

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