* [Qemu-devel] [Bug 1603779] [NEW] AC97 can allocate ~500MB of host RAM
@ 2016-07-17 14:51 Andrew Henderson
2021-05-01 8:06 ` [Bug 1603779] " Thomas Huth
0 siblings, 1 reply; 2+ messages in thread
From: Andrew Henderson @ 2016-07-17 14:51 UTC (permalink / raw)
To: qemu-devel
Public bug reported:
While working with qtest test cases generated via fuzzing with QEMU
2.5.0, I discovered some odd behavior for the AC97 virtual device with
qemu-system-i386. If AC97_MIC_ADC_RATE is set to the value of 1, the
QEMU process allocates over 500MB of additional host RAM. You probably
would not normally notice this on a modern PC, except that I was using a
"ulimit" command to restrict the maximum amount of virtual memory
allowed for the QEMU process, so the process would crash with a SIGTRAP
(signal 5) on the failed memory allocation.
My minimized qtest code to reproduce the issue is:
static void test_crash(void)
{
uint64_t barsize;
dev = get_device();
dev_base[0] = qpci_iomap(dev, 0, &barsize);
dev_base[1] = qpci_iomap(dev, 1, &barsize);
qpci_device_enable(dev);
qpci_io_writew(dev, dev_base[0]+0x32, 0x00000001);
}
I ran a "ulimit -sv 650000" command and then launched the
tests/ac97-test binary with this crash test case included in it. I can
then see the QEMU process crash on an allocation of 722538464 bytes. I
can gradually increase the ulimit memory limit to ~1200000 and then no
longer see the issue, hence my estimate of 500 MB of RAM allocated by
the device.
** Affects: qemu
Importance: Undecided
Status: New
** Tags: ac97
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https://bugs.launchpad.net/bugs/1603779
Title:
AC97 can allocate ~500MB of host RAM
Status in QEMU:
New
Bug description:
While working with qtest test cases generated via fuzzing with QEMU
2.5.0, I discovered some odd behavior for the AC97 virtual device with
qemu-system-i386. If AC97_MIC_ADC_RATE is set to the value of 1, the
QEMU process allocates over 500MB of additional host RAM. You probably
would not normally notice this on a modern PC, except that I was using
a "ulimit" command to restrict the maximum amount of virtual memory
allowed for the QEMU process, so the process would crash with a
SIGTRAP (signal 5) on the failed memory allocation.
My minimized qtest code to reproduce the issue is:
static void test_crash(void)
{
uint64_t barsize;
dev = get_device();
dev_base[0] = qpci_iomap(dev, 0, &barsize);
dev_base[1] = qpci_iomap(dev, 1, &barsize);
qpci_device_enable(dev);
qpci_io_writew(dev, dev_base[0]+0x32, 0x00000001);
}
I ran a "ulimit -sv 650000" command and then launched the
tests/ac97-test binary with this crash test case included in it. I can
then see the QEMU process crash on an allocation of 722538464 bytes. I
can gradually increase the ulimit memory limit to ~1200000 and then no
longer see the issue, hence my estimate of 500 MB of RAM allocated by
the device.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1603779/+subscriptions
^ permalink raw reply [flat|nested] 2+ messages in thread
* [Bug 1603779] Re: AC97 can allocate ~500MB of host RAM
2016-07-17 14:51 [Qemu-devel] [Bug 1603779] [NEW] AC97 can allocate ~500MB of host RAM Andrew Henderson
@ 2021-05-01 8:06 ` Thomas Huth
0 siblings, 0 replies; 2+ messages in thread
From: Thomas Huth @ 2021-05-01 8:06 UTC (permalink / raw)
To: qemu-devel
This is an automated cleanup. This bug report has been moved
to QEMU's new bug tracker on gitlab.com and thus gets marked
as 'expired' now. Please continue with the discussion here:
https://gitlab.com/qemu-project/qemu/-/issues/71
** Changed in: qemu
Status: New => Expired
** Bug watch added: gitlab.com/qemu-project/qemu/-/issues #71
https://gitlab.com/qemu-project/qemu/-/issues/71
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1603779
Title:
AC97 can allocate ~500MB of host RAM
Status in QEMU:
Expired
Bug description:
While working with qtest test cases generated via fuzzing with QEMU
2.5.0, I discovered some odd behavior for the AC97 virtual device with
qemu-system-i386. If AC97_MIC_ADC_RATE is set to the value of 1, the
QEMU process allocates over 500MB of additional host RAM. You probably
would not normally notice this on a modern PC, except that I was using
a "ulimit" command to restrict the maximum amount of virtual memory
allowed for the QEMU process, so the process would crash with a
SIGTRAP (signal 5) on the failed memory allocation.
My minimized qtest code to reproduce the issue is:
static void test_crash(void)
{
uint64_t barsize;
dev = get_device();
dev_base[0] = qpci_iomap(dev, 0, &barsize);
dev_base[1] = qpci_iomap(dev, 1, &barsize);
qpci_device_enable(dev);
qpci_io_writew(dev, dev_base[0]+0x32, 0x00000001);
}
I ran a "ulimit -sv 650000" command and then launched the
tests/ac97-test binary with this crash test case included in it. I can
then see the QEMU process crash on an allocation of 722538464 bytes. I
can gradually increase the ulimit memory limit to ~1200000 and then no
longer see the issue, hence my estimate of 500 MB of RAM allocated by
the device.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1603779/+subscriptions
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2021-05-01 8:21 UTC | newest]
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2016-07-17 14:51 [Qemu-devel] [Bug 1603779] [NEW] AC97 can allocate ~500MB of host RAM Andrew Henderson
2021-05-01 8:06 ` [Bug 1603779] " Thomas Huth
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