[PATCH 4.9 162/165] netfilter: xt_hashlimit: limit the max size of hashtable
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2020-02-27 13:52:05
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From: Cong Wang <redacted> 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: syzbot+adf6c6c2be1c3a718121@syzkaller.appspotmail.com Signed-off-by: Cong Wang <redacted> Reviewed-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/netfilter/xt_hashlimit.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
--- a/net/netfilter/xt_hashlimit.c
+++ b/net/netfilter/xt_hashlimit.c@@ -735,6 +735,8 @@ hashlimit_mt(const struct sk_buff *skb, 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(con 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;