[Patch nf 3/3] xt_hashlimit: limit the max size of hashtable
From: Cong Wang <hidden>
Date: 2020-01-31 20:53:17
Also in:
netfilter-devel
Subsystem:
netfilter, networking [general], the rest · Maintainers:
Pablo Neira Ayuso, Florian Westphal, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
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. The max value is derived from the max value when chosen by the kernel. Reported-and-tested-by: syzbot+adf6c6c2be1c3a718121@syzkaller.appspotmail.com Cc: Pablo Neira Ayuso <pablo@netfilter.org> Cc: Jozsef Kadlecsik <redacted> Cc: Florian Westphal <fw@strlen.de> Signed-off-by: Cong Wang <redacted> --- net/netfilter/xt_hashlimit.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c
index 57a2639bcc22..6327134c5886 100644
--- a/net/netfilter/xt_hashlimit.c
+++ b/net/netfilter/xt_hashlimit.c@@ -272,6 +272,8 @@ dsthash_free(struct xt_hashlimit_htable *ht, struct dsthash_ent *ent) } static void htable_gc(struct work_struct *work); +#define HASHLIMIT_MAX_SIZE 8192 + static int htable_create(struct net *net, struct hashlimit_cfg3 *cfg, const char *name, u_int8_t family, struct xt_hashlimit_htable **out_hinfo,
@@ -290,7 +292,7 @@ static int htable_create(struct net *net, struct hashlimit_cfg3 *cfg, size = (nr_pages << PAGE_SHIFT) / 16384 / sizeof(struct hlist_head); if (nr_pages > 1024 * 1024 * 1024 / PAGE_SIZE) - size = 8192; + size = HASHLIMIT_MAX_SIZE; if (size < 16) size = 16; }
@@ -848,6 +850,8 @@ 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) + return -ENOMEM; if (par->family == NFPROTO_IPV4) { if (cfg->srcmask > 32 || cfg->dstmask > 32) return -EINVAL;
--
2.21.1