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authorChristoph Paasch <christoph.paasch@uclouvain.be>2014-07-29 13:40:57 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-08-14 09:24:15 +0800
commit5191776cd6a25948c6a6622d40e6fe4c2442794a (patch)
tree9119f4354ec83077fcb6b5411a0acc7a136f93ab
parent822fc8dd9dec94a3505998c5febdcb41729f7d57 (diff)
tcp: Fix integer-overflow in TCP vegas
[ Upstream commit 1f74e613ded11517db90b2bd57e9464d9e0fb161 ] In vegas we do a multiplication of the cwnd and the rtt. This may overflow and thus their result is stored in a u64. However, we first need to cast the cwnd so that actually 64-bit arithmetic is done. Then, we need to do do_div to allow this to be used on 32-bit arches. Cc: Stephen Hemminger <stephen@networkplumber.org> Cc: Neal Cardwell <ncardwell@google.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: David Laight <David.Laight@ACULAB.COM> Cc: Doug Leith <doug.leith@nuim.ie> Fixes: 8d3a564da34e (tcp: tcp_vegas cong avoid fix) Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--net/ipv4/tcp_vegas.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/net/ipv4/tcp_vegas.c b/net/ipv4/tcp_vegas.c
index 80fa2bfd7ede..c042e529a11e 100644
--- a/net/ipv4/tcp_vegas.c
+++ b/net/ipv4/tcp_vegas.c
@@ -218,7 +218,8 @@ static void tcp_vegas_cong_avoid(struct sock *sk, u32 ack, u32 in_flight)
* This is:
* (actual rate in segments) * baseRTT
*/
- target_cwnd = tp->snd_cwnd * vegas->baseRTT / rtt;
+ target_cwnd = (u64)tp->snd_cwnd * vegas->baseRTT;
+ do_div(target_cwnd, rtt);
/* Calculate the difference between the window we had,
* and the window we would like to have. This quantity