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Date: Tue, 18 Feb 2020 23:20:54 +0100 From: Pablo Neira Ayuso <pablo@...filter.org> To: netfilter-devel@...r.kernel.org Cc: davem@...emloft.net, netdev@...r.kernel.org Subject: [PATCH 2/9] netfilter: xt_hashlimit: limit the max size of hashtable From: Cong Wang <xiyou.wangcong@...il.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@...kaller.appspotmail.com Signed-off-by: Cong Wang <xiyou.wangcong@...il.com> Reviewed-by: Florian Westphal <fw@...len.de> Signed-off-by: Pablo Neira Ayuso <pablo@...filter.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
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