1 files changed, 1 insertions, 1 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index c3447c5512fd..f0b572fe959a 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3534,7 +3534,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
                 icsk->icsk_retransmits = 0;
         }
 
-        prior_fack = tcp_highest_sack_seq(tp);
+        prior_fack = tcp_is_sack(tp) ? tcp_highest_sack_seq(tp) : tp->snd_una;
         rs.prior_in_flight = tcp_packets_in_flight(tp);
 
         /* ts_recent update must be made after we are sure that the packet