From: Tonghao Zhang <[email protected]>

Don't allow user to create meter unlimitedly,
which may cause to consume a large amount of kernel memory.
The 200,000 meters may be fine in general case.

Cc: Pravin B Shelar <[email protected]>
Cc: Andy Zhou <[email protected]>
Signed-off-by: Tonghao Zhang <[email protected]>
---
 net/openvswitch/meter.c | 21 +++++++++++++++------
 net/openvswitch/meter.h |  1 +
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/net/openvswitch/meter.c b/net/openvswitch/meter.c
index 494a0014ecd8..1b6776f9c109 100644
--- a/net/openvswitch/meter.c
+++ b/net/openvswitch/meter.c
@@ -137,6 +137,7 @@ static int attach_meter(struct dp_meter_table *tbl, struct 
dp_meter *meter)
 {
        struct dp_meter_instance *ti = rcu_dereference_ovsl(tbl->ti);
        u32 hash = meter_hash(ti, meter->id);
+       int err;
 
        /*
         * In generally, slot selected should be empty, because
@@ -148,16 +149,24 @@ static int attach_meter(struct dp_meter_table *tbl, 
struct dp_meter *meter)
        dp_meter_instance_insert(ti, meter);
 
        /* That function is thread-safe. */
-       if (++tbl->count >= ti->n_meters)
-               if (dp_meter_instance_realloc(tbl, ti->n_meters * 2))
-                       goto expand_err;
+       tbl->count++;
+       if (tbl->count > DP_METER_NUM_MAX) {
+               err = -EFBIG;
+               goto attach_err;
+       }
+
+       if (tbl->count >= ti->n_meters &&
+           dp_meter_instance_realloc(tbl, ti->n_meters * 2)) {
+               err = -ENOMEM;
+               goto attach_err;
+       }
 
        return 0;
 
-expand_err:
+attach_err:
        dp_meter_instance_remove(ti, meter);
        tbl->count--;
-       return -ENOMEM;
+       return err;
 }
 
 static void detach_meter(struct dp_meter_table *tbl, struct dp_meter *meter)
@@ -264,7 +273,7 @@ static int ovs_meter_cmd_features(struct sk_buff *skb, 
struct genl_info *info)
        if (IS_ERR(reply))
                return PTR_ERR(reply);
 
-       if (nla_put_u32(reply, OVS_METER_ATTR_MAX_METERS, U32_MAX) ||
+       if (nla_put_u32(reply, OVS_METER_ATTR_MAX_METERS, DP_METER_NUM_MAX) ||
            nla_put_u32(reply, OVS_METER_ATTR_MAX_BANDS, DP_MAX_BANDS))
                goto nla_put_failure;
 
diff --git a/net/openvswitch/meter.h b/net/openvswitch/meter.h
index d91940383bbe..cdfc6b9dbd42 100644
--- a/net/openvswitch/meter.h
+++ b/net/openvswitch/meter.h
@@ -19,6 +19,7 @@ struct datapath;
 
 #define DP_MAX_BANDS           1
 #define DP_METER_ARRAY_SIZE_MIN        (1ULL << 10)
+#define DP_METER_NUM_MAX       (200000ULL)
 
 struct dp_meter_band {
        u32 type;
-- 
2.23.0

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