| From | Luis Henriques <> | Subject | [PATCH 3.11 133/137] tcp: Fix integer-overflow in TCP vegas | Date | Mon, 18 Aug 2014 10:33:14 +0100 |
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3.11.10.15 -stable review patch. If anyone has any objections, please let me know.
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From: Christoph Paasch <christoph.paasch@uclouvain.be>
commit 1f74e613ded11517db90b2bd57e9464d9e0fb161 upstream.
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: Luis Henriques <luis.henriques@canonical.com> --- net/ipv4/tcp_vegas.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
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 -- 1.9.1
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