From: Andrew Morton <akpm@linux-foundation.org>
To: netdev@vger.kernel.org
Cc: "bugme-daemon@kernel-bugs.osdl.org"
<bugme-daemon@bugzilla.kernel.org>,
andsve@gmail.com
Subject: Re: [Bugme-new] [Bug 8536] New: Kernel drops UDP packets silently when reading from certain proc file entries
Date: Thu, 24 May 2007 12:59:26 -0700 [thread overview]
Message-ID: <20070524125926.f91d64a2.akpm@linux-foundation.org> (raw)
In-Reply-To: <200705241948.l4OJmTAe031670@fire-2.osdl.org>
On Thu, 24 May 2007 12:48:29 -0700
bugme-daemon@bugzilla.kernel.org wrote:
> http://bugzilla.kernel.org/show_bug.cgi?id=8536
>
> Summary: Kernel drops UDP packets silently when reading from
> certain proc file entries
> Kernel Version: 2.6.x
> Status: NEW
> Severity: high
> Owner: acme@ghostprotocols.net
> Submitter: andsve@gmail.com
>
>
> Most recent kernel where this bug did *NOT* occur:
> I do not know, but I now that it exists in RHEL4 2.6.9.x kernels
> Distribution:
> All
> Hardware Environment:
> Multi core SMP
> Software Environment:
> All
> Problem Description:
> It is possible to introduce UDP packet losses by reading
> the proc file entry /proc/net/tcp. The really strange thing is that
> the error counters for packet drops are not increased.
> This means that the kernel introduce "silent" packet drops by just reading a
> proc statistics entry which is Not a good thing! I can most probably be used for
> denial of service attacks from no root users.
>
> When looking at the network code it does not seem possible that silent packet
> drops can ocurr so it is probably a quite nasty kernel bug.
>
>
> Steps to reproduce:
>
> * Send high speed RTP/UDP multicast traffic towards the system, 50Mbit/s.
>
> * Receive the RTP packets and check/validate the RTP counters and print out when
> the counter is not continous.
>
> * Do a while loop cat:ing from the /proc/net/tcp and see the packets beeing
> dropped but not accounted for in the counter statistics.
>
> I have reproduced this behavior on all our systems ranging from dual to quad
> core Xeon and Opteron and also on different OS releases, RHEL4, RHEL5, Fedora
> Core 5 and 6
>
next parent reply other threads:[~2007-05-24 19:59 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200705241948.l4OJmTAe031670@fire-2.osdl.org>
2007-05-24 19:59 ` Andrew Morton [this message]
2007-05-25 6:23 ` [Bugme-new] [Bug 8536] New: Kernel drops UDP packets silently when reading from certain proc file entries Herbert Xu
2007-05-25 6:50 ` Eric Dumazet
2007-05-25 6:57 ` Herbert Xu
2007-05-25 7:15 ` Eric Dumazet
2007-05-25 7:17 ` Herbert Xu
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