Thread (202 messages) 202 messages, 6 authors, 2014-09-17
STALE4323d

[PATCH 3.13 006/187] tcp: Fix integer-overflows in TCP veno

From: Kamal Mostafa <hidden>
Date: 2014-09-15 23:22:38
Also in: lkml
Subsystem: networking [general], networking [tcp], the rest · Maintainers: "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Neal Cardwell, Linus Torvalds

3.13.11.7 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Christoph Paasch <redacted>

[ 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 <redacted>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Kamal Mostafa <redacted>
---
 net/ipv4/tcp_veno.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/ipv4/tcp_veno.c b/net/ipv4/tcp_veno.c
index 326475a..603ad49 100644
--- a/net/ipv4/tcp_veno.c
+++ b/net/ipv4/tcp_veno.c
@@ -145,7 +145,7 @@ static void tcp_veno_cong_avoid(struct sock *sk, u32 ack, u32 acked,
 
 		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);
 
-- 
1.9.1
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