From 782077bff3a68b5ed7e711d7c58792cb26e8c92c Mon Sep 17 00:00:00 2001 From: Cong Wang Date: Sun, 2 Feb 2020 20:30:52 -0800 Subject: [PATCH] netfilter: xt_hashlimit: reduce hashlimit_mutex scope for htable_put() commit c4a3922d2d20c710f827d3a115ee338e8d0467df upstream. It is unnecessary to hold hashlimit_mutex for htable_destroy() as it is already removed from the global hashtable and its refcount is already zero. Also, switch hinfo->use to refcount_t so that we don't have to hold the mutex until it reaches zero in htable_put(). Reported-and-tested-by: syzbot+adf6c6c2be1c3a718121@syzkaller.appspotmail.com Acked-by: Florian Westphal Signed-off-by: Cong Wang Signed-off-by: Pablo Neira Ayuso Signed-off-by: Greg Kroah-Hartman --- net/netfilter/xt_hashlimit.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c index 6520d9e..1b68a13 100644 --- a/net/netfilter/xt_hashlimit.c +++ b/net/netfilter/xt_hashlimit.c @@ -36,6 +36,7 @@ #include #include #include +#include #include #define XT_HASHLIMIT_ALL (XT_HASHLIMIT_HASH_DIP | XT_HASHLIMIT_HASH_DPT | \ @@ -114,7 +115,7 @@ struct dsthash_ent { struct xt_hashlimit_htable { struct hlist_node node; /* global list of all htables */ - int use; + refcount_t use; u_int8_t family; bool rnd_initialized; @@ -315,7 +316,7 @@ static int htable_create(struct net *net, struct hashlimit_cfg3 *cfg, for (i = 0; i < hinfo->cfg.size; i++) INIT_HLIST_HEAD(&hinfo->hash[i]); - hinfo->use = 1; + refcount_set(&hinfo->use, 1); hinfo->count = 0; hinfo->family = family; hinfo->rnd_initialized = false; @@ -434,7 +435,7 @@ static struct xt_hashlimit_htable *htable_find_get(struct net *net, hlist_for_each_entry(hinfo, &hashlimit_net->htables, node) { if (!strcmp(name, hinfo->name) && hinfo->family == family) { - hinfo->use++; + refcount_inc(&hinfo->use); return hinfo; } } @@ -443,12 +444,11 @@ static struct xt_hashlimit_htable *htable_find_get(struct net *net, static void htable_put(struct xt_hashlimit_htable *hinfo) { - mutex_lock(&hashlimit_mutex); - if (--hinfo->use == 0) { + if (refcount_dec_and_mutex_lock(&hinfo->use, &hashlimit_mutex)) { hlist_del(&hinfo->node); + mutex_unlock(&hashlimit_mutex); htable_destroy(hinfo); } - mutex_unlock(&hashlimit_mutex); } /* The algorithm used is the Simple Token Bucket Filter (TBF) -- 2.7.4