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-rw-r--r--net/netfilter/xt_hashlimit.c25
1 files changed, 21 insertions, 4 deletions
diff --git a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c
index 30ad0b6241a1..a9d7af953ceb 100644
--- a/net/netfilter/xt_hashlimit.c
+++ b/net/netfilter/xt_hashlimit.c
@@ -157,11 +157,22 @@ dsthash_find(const struct xt_hashlimit_htable *ht,
/* allocate dsthash_ent, initialize dst, put in htable and lock it */
static struct dsthash_ent *
dsthash_alloc_init(struct xt_hashlimit_htable *ht,
- const struct dsthash_dst *dst)
+ const struct dsthash_dst *dst, bool *race)
{
struct dsthash_ent *ent;
spin_lock(&ht->lock);
+
+ /* Two or more packets may race to create the same entry in the
+ * hashtable, double check if this packet lost race.
+ */
+ ent = dsthash_find(ht, dst);
+ if (ent != NULL) {
+ spin_unlock(&ht->lock);
+ *race = true;
+ return ent;
+ }
+
/* initialize hash with random val at the time we allocate
* the first hashtable entry */
if (unlikely(!ht->rnd_initialized)) {
@@ -588,6 +599,7 @@ hashlimit_mt(const struct sk_buff *skb, struct xt_action_param *par)
unsigned long now = jiffies;
struct dsthash_ent *dh;
struct dsthash_dst dst;
+ bool race = false;
u32 cost;
if (hashlimit_init_dst(hinfo, &dst, skb, par->thoff) < 0)
@@ -596,13 +608,18 @@ hashlimit_mt(const struct sk_buff *skb, struct xt_action_param *par)
rcu_read_lock_bh();
dh = dsthash_find(hinfo, &dst);
if (dh == NULL) {
- dh = dsthash_alloc_init(hinfo, &dst);
+ dh = dsthash_alloc_init(hinfo, &dst, &race);
if (dh == NULL) {
rcu_read_unlock_bh();
goto hotdrop;
+ } else if (race) {
+ /* Already got an entry, update expiration timeout */
+ dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
+ rateinfo_recalc(dh, now, hinfo->cfg.mode);
+ } else {
+ dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
+ rateinfo_init(dh, hinfo);
}
- dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
- rateinfo_init(dh, hinfo);
} else {
/* update expiration timeout */
dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);