* [Qemu-devel] [Bug 1054180] [NEW] DNS activity in slirp (user networking) mode quickly depletes file descriptors and crashes qemu
@ 2012-09-21 16:13 Michal Svoboda
2017-08-21 7:47 ` [Qemu-devel] [Bug 1054180] " Thomas Huth
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: Michal Svoboda @ 2012-09-21 16:13 UTC (permalink / raw)
To: qemu-devel
Public bug reported:
Hi, we have encountered quite some trouble with filedescriptor depletion
of the qemu process. We have figured out that it can be demonstrated
easily by doing a lot of DNS queries inside the VM -- in our real world
scenario this is caused by running centos network install with a fast
mirror.
This situation is further problematic because qemu can't handle fd depletion very well:
1) if ulimit is 1024 then qemu hangs in infinite loop whenever it tries to open the 1025th fd
2) setting ulimit >1024 does not help that much because qemu uses select and max. fd set size is 1024 per default => qemu crashes because of buffer overflow in select()
3) setting ulimit > 1024 AND recompiling with large enough fd set size AND disabling gcc's fortify source seems to work, but that's really just a hot-fix
The problem can be replicated quite easily by running something like
while :; do echo >/dev/udp/10.0.2.3/53; done
inside a Linux VM -- crash comes very soon.
This problem is present in current qemu (1.2.0) and in earlier as well.
** Affects: qemu
Importance: Undecided
Status: New
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You received this bug notification because you are a member of qemu-
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https://bugs.launchpad.net/bugs/1054180
Title:
DNS activity in slirp (user networking) mode quickly depletes file
descriptors and crashes qemu
Status in QEMU:
New
Bug description:
Hi, we have encountered quite some trouble with filedescriptor
depletion of the qemu process. We have figured out that it can be
demonstrated easily by doing a lot of DNS queries inside the VM -- in
our real world scenario this is caused by running centos network
install with a fast mirror.
This situation is further problematic because qemu can't handle fd depletion very well:
1) if ulimit is 1024 then qemu hangs in infinite loop whenever it tries to open the 1025th fd
2) setting ulimit >1024 does not help that much because qemu uses select and max. fd set size is 1024 per default => qemu crashes because of buffer overflow in select()
3) setting ulimit > 1024 AND recompiling with large enough fd set size AND disabling gcc's fortify source seems to work, but that's really just a hot-fix
The problem can be replicated quite easily by running something like
while :; do echo >/dev/udp/10.0.2.3/53; done
inside a Linux VM -- crash comes very soon.
This problem is present in current qemu (1.2.0) and in earlier as
well.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1054180/+subscriptions
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Qemu-devel] [Bug 1054180] Re: DNS activity in slirp (user networking) mode quickly depletes file descriptors and crashes qemu
2012-09-21 16:13 [Qemu-devel] [Bug 1054180] [NEW] DNS activity in slirp (user networking) mode quickly depletes file descriptors and crashes qemu Michal Svoboda
@ 2017-08-21 7:47 ` Thomas Huth
2017-08-21 7:48 ` Thomas Huth
2017-10-21 4:17 ` Launchpad Bug Tracker
2 siblings, 0 replies; 4+ messages in thread
From: Thomas Huth @ 2017-08-21 7:47 UTC (permalink / raw)
To: qemu-devel
Triaging old bug tickets ... can you still reproduce this problem with
the latest version of QEMU (currently v2.9 or a release candidate of
2.10)?
** Changed in: qemu
Status: New => Incomplete
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You received this bug notification because you are a member of qemu-
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https://bugs.launchpad.net/bugs/1054180
Title:
DNS activity in slirp (user networking) mode quickly depletes file
descriptors and crashes qemu
Status in QEMU:
Incomplete
Bug description:
Hi, we have encountered quite some trouble with filedescriptor
depletion of the qemu process. We have figured out that it can be
demonstrated easily by doing a lot of DNS queries inside the VM -- in
our real world scenario this is caused by running centos network
install with a fast mirror.
This situation is further problematic because qemu can't handle fd depletion very well:
1) if ulimit is 1024 then qemu hangs in infinite loop whenever it tries to open the 1025th fd
2) setting ulimit >1024 does not help that much because qemu uses select and max. fd set size is 1024 per default => qemu crashes because of buffer overflow in select()
3) setting ulimit > 1024 AND recompiling with large enough fd set size AND disabling gcc's fortify source seems to work, but that's really just a hot-fix
The problem can be replicated quite easily by running something like
while :; do echo >/dev/udp/10.0.2.3/53; done
inside a Linux VM -- crash comes very soon.
This problem is present in current qemu (1.2.0) and in earlier as
well.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1054180/+subscriptions
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Qemu-devel] [Bug 1054180] Re: DNS activity in slirp (user networking) mode quickly depletes file descriptors and crashes qemu
2012-09-21 16:13 [Qemu-devel] [Bug 1054180] [NEW] DNS activity in slirp (user networking) mode quickly depletes file descriptors and crashes qemu Michal Svoboda
2017-08-21 7:47 ` [Qemu-devel] [Bug 1054180] " Thomas Huth
@ 2017-08-21 7:48 ` Thomas Huth
2017-10-21 4:17 ` Launchpad Bug Tracker
2 siblings, 0 replies; 4+ messages in thread
From: Thomas Huth @ 2017-08-21 7:48 UTC (permalink / raw)
To: qemu-devel
Also could you please provide the exact command line that you use to
start QEMU?
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1054180
Title:
DNS activity in slirp (user networking) mode quickly depletes file
descriptors and crashes qemu
Status in QEMU:
Incomplete
Bug description:
Hi, we have encountered quite some trouble with filedescriptor
depletion of the qemu process. We have figured out that it can be
demonstrated easily by doing a lot of DNS queries inside the VM -- in
our real world scenario this is caused by running centos network
install with a fast mirror.
This situation is further problematic because qemu can't handle fd depletion very well:
1) if ulimit is 1024 then qemu hangs in infinite loop whenever it tries to open the 1025th fd
2) setting ulimit >1024 does not help that much because qemu uses select and max. fd set size is 1024 per default => qemu crashes because of buffer overflow in select()
3) setting ulimit > 1024 AND recompiling with large enough fd set size AND disabling gcc's fortify source seems to work, but that's really just a hot-fix
The problem can be replicated quite easily by running something like
while :; do echo >/dev/udp/10.0.2.3/53; done
inside a Linux VM -- crash comes very soon.
This problem is present in current qemu (1.2.0) and in earlier as
well.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1054180/+subscriptions
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Qemu-devel] [Bug 1054180] Re: DNS activity in slirp (user networking) mode quickly depletes file descriptors and crashes qemu
2012-09-21 16:13 [Qemu-devel] [Bug 1054180] [NEW] DNS activity in slirp (user networking) mode quickly depletes file descriptors and crashes qemu Michal Svoboda
2017-08-21 7:47 ` [Qemu-devel] [Bug 1054180] " Thomas Huth
2017-08-21 7:48 ` Thomas Huth
@ 2017-10-21 4:17 ` Launchpad Bug Tracker
2 siblings, 0 replies; 4+ messages in thread
From: Launchpad Bug Tracker @ 2017-10-21 4:17 UTC (permalink / raw)
To: qemu-devel
[Expired for QEMU because there has been no activity for 60 days.]
** Changed in: qemu
Status: Incomplete => Expired
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1054180
Title:
DNS activity in slirp (user networking) mode quickly depletes file
descriptors and crashes qemu
Status in QEMU:
Expired
Bug description:
Hi, we have encountered quite some trouble with filedescriptor
depletion of the qemu process. We have figured out that it can be
demonstrated easily by doing a lot of DNS queries inside the VM -- in
our real world scenario this is caused by running centos network
install with a fast mirror.
This situation is further problematic because qemu can't handle fd depletion very well:
1) if ulimit is 1024 then qemu hangs in infinite loop whenever it tries to open the 1025th fd
2) setting ulimit >1024 does not help that much because qemu uses select and max. fd set size is 1024 per default => qemu crashes because of buffer overflow in select()
3) setting ulimit > 1024 AND recompiling with large enough fd set size AND disabling gcc's fortify source seems to work, but that's really just a hot-fix
The problem can be replicated quite easily by running something like
while :; do echo >/dev/udp/10.0.2.3/53; done
inside a Linux VM -- crash comes very soon.
This problem is present in current qemu (1.2.0) and in earlier as
well.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1054180/+subscriptions
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2017-10-21 4:30 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2012-09-21 16:13 [Qemu-devel] [Bug 1054180] [NEW] DNS activity in slirp (user networking) mode quickly depletes file descriptors and crashes qemu Michal Svoboda
2017-08-21 7:47 ` [Qemu-devel] [Bug 1054180] " Thomas Huth
2017-08-21 7:48 ` Thomas Huth
2017-10-21 4:17 ` Launchpad Bug Tracker
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