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authorLachlan Andrew <lachlan.andrew@gmail.com>2008-04-30 12:04:03 +0400
committerDavid S. Miller <davem@davemloft.net>2008-04-30 12:04:03 +0400
commit159131149c2f56c1da5ae5e23ab9d5acef4916d1 (patch)
tree7ad3fc498c27fd8dfdf4a1fcf506b1220919f715 /net/ipv4/tcp_veno.c
parentbe9164e769d57aa10b2bbe15d103edc041b9e7de (diff)
downloadlinux-159131149c2f56c1da5ae5e23ab9d5acef4916d1.tar.xz
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.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/net/ipv4/tcp_veno.c b/net/ipv4/tcp_veno.c
index d16689e98516..2bf618a3b00b 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;