TCP: tcp_hybla: Fix integer overflow in slow start increment

For large values of rtt, 2^rho operation may overflow u32. Clamp down the increment to 2^16.

Signed-off-by: Daniele Lacamera <root@danielinux.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/tcp_hybla.c b/net/ipv4/tcp_hybla.c
index c209e05..377bc93 100644 (file)
--- a/net/ipv4/tcp_hybla.c
+++ b/net/ipv4/tcp_hybla.c
@@ -126,8 +126,8 @@ static void hybla_cong_avoid(struct sock *sk, u32 ack, u32 in_flight)
                 * calculate 2^fract in a <<7 value.
                 */
                is_slowstart = 1;
-               increment = ((1 << ca->rho) * hybla_fraction(rho_fractions))
-                       - 128;
+               increment = ((1 << min(ca->rho, 16U)) *
+                       hybla_fraction(rho_fractions)) - 128;
        } else {
                /*
                 * congestion avoidance