netdev - Re: bug in qavg calculation in include/net/red.h (resending as plain-text email)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1325794400.2748.1.camel@edumazet-laptop>
Date:	Thu, 05 Jan 2012 21:13:20 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	"Yalagandula, Praveen" <praveen.yalagandula@...com>
Cc:	Alexey Kuznetsov <kuznet@....inr.ac.ru>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: bug in qavg calculation in include/net/red.h (resending as
 plain-text email)

Le jeudi 05 janvier 2012 à 19:30 +0000, Yalagandula, Praveen a écrit :
> (Resending as plain text)
> 
> Dear Alexey,
> 
> The code (see below) for computing the queue average for RED
> implementation in Linux kernel has a bug. The return line should be
> "return p->qavg + ((backlog - p->qavg) >> p->Wlog);". 
> 
> qavg = qavg*(1-W) + backlog*W
> 
>      = qavg + (backlog-qavg)*W
> 
> The current buggy code applies right shift to only the previous qavg,
> where as it should be applied to (backlog - qavg). Hope you can get
> this bug corrected.

Code is correct.

Please read the comment, it really explains the thing.

Thanks


--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html