1 files changed, 7 insertions, 2 deletions

diff --git a/net/ipv4/tcp_cubic.c b/net/ipv4/tcp_cubic.c
index 34340c9c95fa..f376b05cca81 100644
--- a/net/ipv4/tcp_cubic.c
+++ b/net/ipv4/tcp_cubic.c
@@ -93,6 +93,7 @@ struct bictcp {
         u32     ack_cnt;        /* number of acks */
         u32     tcp_cwnd;       /* estimated tcp cwnd */
 #define ACK_RATIO_SHIFT 4
+#define ACK_RATIO_LIMIT (32u << ACK_RATIO_SHIFT)
         u16     delayed_ack;    /* estimate the ratio of Packets/ACKs << 4 */
         u8      sample_cnt;     /* number of samples to decide curr_rtt */
         u8      found;          /* the exit point is found? */
@@ -398,8 +399,12 @@ static void bictcp_acked(struct sock *sk, u32 cnt, s32 rtt_us)
         u32 delay;
 
         if (icsk->icsk_ca_state == TCP_CA_Open) {
-                cnt -= ca->delayed_ack >> ACK_RATIO_SHIFT;
-                ca->delayed_ack += cnt;
+                u32 ratio = ca->delayed_ack;
+
+                ratio -= ca->delayed_ack >> ACK_RATIO_SHIFT;
+                ratio += cnt;
+
+                ca->delayed_ack = min(ratio, ACK_RATIO_LIMIT);
         }
 
         /* Some calls are for duplicates without timetamps */