| From foo@baz Fri Aug 8 09:25:59 PDT 2014 |
| From: Christoph Paasch <christoph.paasch@uclouvain.be> |
| Date: Tue, 29 Jul 2014 12:07:27 +0200 |
| Subject: tcp: Fix integer-overflows in TCP veno |
| |
| From: Christoph Paasch <christoph.paasch@uclouvain.be> |
| |
| [ Upstream commit 45a07695bc64b3ab5d6d2215f9677e5b8c05a7d0 ] |
| |
| In veno 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. |
| |
| A first attempt at fixing 76f1017757aa0 ([TCP]: TCP Veno congestion |
| control) was made by 159131149c2 (tcp: Overflow bug in Vegas), but it |
| failed to add the required cast in tcp_veno_cong_avoid(). |
| |
| Fixes: 76f1017757aa0 ([TCP]: TCP Veno congestion control) |
| 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> |
| --- |
| net/ipv4/tcp_veno.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| --- a/net/ipv4/tcp_veno.c |
| +++ b/net/ipv4/tcp_veno.c |
| @@ -144,7 +144,7 @@ static void tcp_veno_cong_avoid(struct s |
| |
| rtt = veno->minrtt; |
| |
| - target_cwnd = (tp->snd_cwnd * veno->basertt); |
| + target_cwnd = (u64)tp->snd_cwnd * veno->basertt; |
| target_cwnd <<= V_PARAM_SHIFT; |
| do_div(target_cwnd, rtt); |
| |
