Message ID | 20200203043053.19192-4-xiyou.wangcong@gmail.com |
---|---|
State | Accepted |
Delegated to: | Pablo Neira |
Headers | show |
Series | netfilter: xt_hashlimit: a few improvements | expand |
Cong Wang <xiyou.wangcong@gmail.com> wrote: > 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. Reviewed-by: Florian Westphal <fw@strlen.de>
On Sun, Feb 02, 2020 at 08:30:53PM -0800, Cong Wang wrote: > 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. Also applied, thanks.
diff --git a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c index 06e59f9d9f62..60c023630d14 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;
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 Cc: Pablo Neira Ayuso <pablo@netfilter.org> Cc: Jozsef Kadlecsik <kadlec@netfilter.org> Cc: Florian Westphal <fw@strlen.de> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> --- net/netfilter/xt_hashlimit.c | 10 ++++++++++ 1 file changed, 10 insertions(+)