[libvirt] [PATCH] util: fix crash in virClassIsDerivedFrom for CloseCallbacks objects
Michal Privoznik
mprivozn at redhat.com
Tue Sep 6 14:42:44 UTC 2016
On 05.09.2016 18:42, Maxim Nestratov wrote:
> There is a possibility that qemu driver frees by unreferencing its
> closeCallbacks pointer as it has the only reference to the object,
> while in fact not all users of CloseCallbacks called thier
> virCloseCallbacksUnset.
>
> Backtrace is the following:
> Thread #1:
> 0 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
> 1 in virCondWait (c=<optimized out>, m=<optimized out>)
> at util/virthread.c:154
> 2 in virThreadPoolFree (pool=0x7f0810110b50)
> at util/virthreadpool.c:266
> 3 in qemuStateCleanup () at qemu/qemu_driver.c:1116
> 4 in virStateCleanup () at libvirt.c:808
> 5 in main (argc=<optimized out>, argv=<optimized out>)
> at libvirtd.c:1660
>
> Thread #2:
> 0 in virClassIsDerivedFrom (klass=0xdeadbeef, parent=0x7f0837c694d0) at util/virobject.c:169
> 1 in virObjectIsClass (anyobj=anyobj at entry=0x7f08101d4760, klass=<optimized out>) at util/virobject.c:365
> 2 in virObjectLock (anyobj=0x7f08101d4760) at util/virobject.c:317
> 3 in virCloseCallbacksUnset (closeCallbacks=0x7f08101d4760, vm=vm at entry=0x7f08101d47b0, cb=cb at entry=0x7f081d078fc0 <qemuProcessAutoDestroy>) at util/virclosecallbacks.c:163
> 4 in qemuProcessAutoDestroyRemove (driver=driver at entry=0x7f081018be50, vm=vm at entry=0x7f08101d47b0) at qemu/qemu_process.c:6368
> 5 in qemuProcessStop (driver=driver at entry=0x7f081018be50, vm=vm at entry=0x7f08101d47b0, reason=reason at entry=VIR_DOMAIN_SHUTOFF_SHUTDOWN, asyncJob=asyncJob at entry=QEMU_ASYNC_JOB_NONE, flags=flags at entry=0) at qemu/qemu_process.c:5854
> 6 in processMonitorEOFEvent (vm=0x7f08101d47b0, driver=0x7f081018be50) at qemu/qemu_driver.c:4585
> 7 qemuProcessEventHandler (data=<optimized out>, opaque=0x7f081018be50) at qemu/qemu_driver.c:4629
> 8 in virThreadPoolWorker (opaque=opaque at entry=0x7f0837c4f820) at util/virthreadpool.c:145
> 9 in virThreadHelper (data=<optimized out>) at util/virthread.c:206
> 10 in start_thread () from /lib64/libpthread.so.0
>
> Let's reference CloseCallbacks object in virCloseCallbacksSet and
> unreference in virCloseCallbacksUnset.
>
> Signed-off-by: Maxim Nestratov <mnestratov at virtuozzo.com>
> ---
> src/util/virclosecallbacks.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/src/util/virclosecallbacks.c b/src/util/virclosecallbacks.c
> index 82d4071..891a92b 100644
> --- a/src/util/virclosecallbacks.c
> +++ b/src/util/virclosecallbacks.c
> @@ -141,6 +141,7 @@ virCloseCallbacksSet(virCloseCallbacksPtr closeCallbacks,
> virObjectRef(vm);
> }
>
> + virObjectRef(closeCallbacks);
> ret = 0;
> cleanup:
> virObjectUnlock(closeCallbacks);
> @@ -180,6 +181,8 @@ virCloseCallbacksUnset(virCloseCallbacksPtr closeCallbacks,
> ret = 0;
> cleanup:
> virObjectUnlock(closeCallbacks);
> + if (!ret)
> + virObjectUnref(closeCallbacks);
Might as well put this a few lines above, just before 'ret = 0' line.
ACK with that changed.
Michal
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