On Thu, 24 May 2007 12:48:29 -0700 [EMAIL PROTECTED] 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: [EMAIL PROTECTED] > Submitter: [EMAIL PROTECTED] > > > 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 > - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
