diff options
| author | Lachlan Andrew <lachlan.andrew@gmail.com> | 2008-04-30 01:04:03 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2008-04-30 01:04:03 -0700 |
| commit | 159131149c2f56c1da5ae5e23ab9d5acef4916d1 (patch) | |
| tree | 7ad3fc498c27fd8dfdf4a1fcf506b1220919f715 /net/ipv4/tcp_veno.c | |
| parent | be9164e769d57aa10b2bbe15d103edc041b9e7de (diff) | |
tcp: Overflow bug in Vegas
From: Lachlan Andrew <lachlan.andrew@gmail.com>
There is an overflow bug in net/ipv4/tcp_vegas.c for large BDPs
(e.g. 400Mbit/s, 400ms). The multiplication (old_wnd *
vegas->baseRTT) << V_PARAM_SHIFT overflows a u32.
[ Fix tcp_veno.c too, it has similar calculations. -DaveM ]
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_veno.c')
| -rw-r--r-- | net/ipv4/tcp_veno.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/net/ipv4/tcp_veno.c b/net/ipv4/tcp_veno.c index d16689e9851..2bf618a3b00 100644 --- a/net/ipv4/tcp_veno.c +++ b/net/ipv4/tcp_veno.c @@ -133,7 +133,8 @@ static void tcp_veno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight) */ tcp_reno_cong_avoid(sk, ack, in_flight); } else { - u32 rtt, target_cwnd; + u64 target_cwnd; + u32 rtt; /* We have enough rtt samples, so, using the Veno * algorithm, we determine the state of the network. @@ -141,8 +142,9 @@ static void tcp_veno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight) rtt = veno->minrtt; - target_cwnd = ((tp->snd_cwnd * veno->basertt) - << V_PARAM_SHIFT) / rtt; + target_cwnd = (tp->snd_cwnd * veno->basertt); + target_cwnd <<= V_PARAM_SHIFT; + do_div(target_cwnd, rtt); veno->diff = (tp->snd_cwnd << V_PARAM_SHIFT) - target_cwnd; |