[libvirt] RHBZ 1013045: Crash on xen domain startup

[Jeremy Fitzhardinge]

On 10/24/2013 02:52 AM, Martin Kletzander wrote:
> On Wed, Oct 23, 2013 at 10:46:14AM -0700, Jeremy Fitzhardinge wrote:
>> Hi all,
>>
>> I posted this bug (https://bugzilla.redhat.com/show_bug.cgi?id=1013045)
>> to the Redhat Bugzilla a while ago, and the only response has been to
>> post a note to this list about the bug.
>>
>> Summary below, but it looks like a pretty clear use-after-free or
>> something. The full details are attached to the bug report.
>>
>
> From the looks of the BZ, I think the probnlem found by valgrind (not
> the one in libxl) is a different than the one which causes the
> 'invalid free()', but anyway, I posted a patch [1] which might help
> (read: fixes a problem found out thanks to the valgrind output), but I
> have no way to test it.  If you do, I would appreciate you trying
> whether the issue gets fixed for you with that patch.

Actually, the (original) code in question looks completely bogus. It's
casting a virBitmap * into a uint8_t * and then inspecting it
byte-by-byte, whereas it looks like it should be using the bit-test API.

I'm reworking it at the moment.

    J
>
>
> Thank you,
> Martin
>
> [1] https://www.redhat.com/archives/libvir-list/2013-October/msg01075.html
>
>> Thanks,
>>
>>     J
>>
>>
>> --
>> Description of problem:
>> When starting a Xen domain with libvirt + libxl, it crashes after
>> creating the domain.  The domain is left in a paused state, and works
>> fine if manually unpaused with xl unpause. virt-manager never shows the
>> domain as running.
>>
>> [...]
>>
>> Steps to Reproduce:
>> 1. Open virt-manager
>> 2. Connect to localhost (xen)
>> 3. Start a domain
>>
>> Actual results:
>> Domain is created in a paused state, virt-manager shows errors about
>> losing connection to the daemon. Logs show libvirtd crashed.
>>
>> Expected results:
>> Domain creation.
>>
>> Additional info:
>> Sep 27 09:08:30 saboo libvirtd[24880]: *** Error in
>> `/usr/sbin/libvirtd': free(): invalid next size (fast):
>> 0x00007f82c8003210 ***
>> Sep 27 09:08:30 saboo libvirtd[24880]: ======= Backtrace: =========
>> Sep 27 09:08:30 saboo libvirtd[24880]:
>> /lib64/libc.so.6(+0x365b27d0e8)[0x7f82f5a7a0e8]
>> Sep 27 09:08:30 saboo libvirtd[24880]:
>> /lib64/libvirt.so.0(virFree+0x1a)[0x7f82f8f07d5a]
>> Sep 27 09:08:30 saboo libvirtd[24880]:
>>
/usr/lib64/libvirt/connection-driver/libvirt_driver_libxl.so(+0x14b6c)[0x7f82e032bb6c]
>> Sep 27 09:08:30 saboo libvirtd[24880]:
>>
/usr/lib64/libvirt/connection-driver/libvirt_driver_libxl.so(+0x154d4)[0x7f82e032c4d4]
>> Sep 27 09:08:30 saboo libvirtd[24880]:
>> /lib64/libvirt.so.0(virDomainCreate+0xf7)[0x7f82f8fdb6b7]
>> Sep 27 09:08:30 saboo libvirtd[24880]:
>> /usr/sbin/libvirtd(+0x350c7)[0x7f82f9a1a0c7]
>> Sep 27 09:08:30 saboo libvirtd[24880]:
>> /lib64/libvirt.so.0(virNetServerProgramDispatch+0x3ba)[0x7f82f90314aa]
>> Sep 27 09:08:30 saboo libvirtd[24880]:
>> /lib64/libvirt.so.0(+0x3a33f822d8)[0x7f82f902c2d8]
>> Sep 27 09:08:30 saboo libvirtd[24880]:
>> /lib64/libvirt.so.0(+0x3a33ea0c15)[0x7f82f8f4ac15]
>> Sep 27 09:08:30 saboo libvirtd[24880]:
>> /lib64/libvirt.so.0(+0x3a33ea0691)[0x7f82f8f4a691]
>> Sep 27 09:08:30 saboo libvirtd[24880]:
>> /lib64/libpthread.so.0(+0x365ba07c53)[0x7f82f61ccc53]
>> Sep 27 09:08:30 saboo libvirtd[24880]:
>> /lib64/libc.so.6(clone+0x6d)[0x7f82f5af2d3d]
>>
>>
>>
>> --
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