From: Cong Wang xiyou.wangcong@gmail.com
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 xiyou.wangcong@gmail.com 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 @@ -851,6 +851,8 @@ hashlimit_mt(const struct sk_buff *skb, 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, @@ -861,6 +863,14 @@ 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;