[libvirt] Entering freeze for libvirt-4.6.0

[Michal Privoznik]

On 07/30/2018 05:20 PM, Andrea Bolognani wrote:
> On Sat, 2018-07-28 at 21:56 +0800, Daniel Veillard wrote:
>>

> 
> Unfortunately I've spotted an issue during my testing of rc1 today:
> with the libvirt_guest NSS module enabled, Evolution would crash a
> few seconds after being started. Here's the stack trace:
> 
>   #0  0x00007fffe7b69ba5 in json_object_iter_next () at /lib64/libjson-glib-1.0.so.0
>   #1  0x00007fffad8e757b in virJSONValueFromJansson () at /lib64/libnss_libvirt_guest.so.2
>   #2  0x00007fffad8e75d8 in virJSONValueFromJansson () at /lib64/libnss_libvirt_guest.so.2
>   #3  0x00007fffad8e8994 in virJSONValueFromString () at /lib64/libnss_libvirt_guest.so.2
>   #4  0x00007fffad8ecb5a in virMacMapNew () at /lib64/libnss_libvirt_guest.so.2
>   #5  0x00007fffad8cc140 in findLease () at /lib64/libnss_libvirt_guest.so.2
>   #6  0x00007fffad8ccb1c in _nss_libvirt_guest_gethostbyname4_r () at /lib64/libnss_libvirt_guest.so.2
>   #7  0x00007fffeb2599d2 in gaih_inet.constprop () at /lib64/libc.so.6
>   #8  0x00007fffeb25aab4 in getaddrinfo () at /lib64/libc.so.6
>   #9  0x00007ffff1d41a04 in do_lookup_by_name () at /lib64/libgio-2.0.so.0
>   #10 0x00007ffff1d3e937 in g_task_thread_pool_thread () at /lib64/libgio-2.0.so.0
>   #11 0x00007ffff5c39933 in g_thread_pool_thread_proxy () at /lib64/libglib-2.0.so.0
>   #12 0x00007ffff5c38f2a in g_thread_proxy () at /lib64/libglib-2.0.so.0
>   #13 0x00007ffff6314594 in start_thread () at /lib64/libpthread.so.0
>   #14 0x00007fffeb2700df in clone () at /lib64/libc.so.6
> 
> I've talked about it with a few colleagues and we believe the issue
> to be caused by jansson and json-glib both exporting a symbol called
> json_object_iter_next: Evolution itself (indirectly?) links against
> the latter library, so when the libvirt_guest NSS module is loaded
> and attempts to process JSON using the former, it picks up the wrong
> implementation, leading to a crash. gnome-boxes also crashes with
> the same stack trace.

Worse. querying gentoo portage I've found some important packages
requiring json-glib:

x11-libs/gtk
gnome-base/gnome-shell

So once users of these app update to latest libvirt they will see the
crashes.

> 
> It seems like a similar issue could affect any application linking
> both to libvirt and json-glib, regardless of whether or not the NSS
> plugin has been enabled, which is of course pretty bad.

Yes, any application can crash.

> 
> Unfortunately, I don't have any bright ideas on how to solve this,
> so anyone who might: please step forward! We're just a few days
> away from the next release, and if we can't figure out a way around
> this soon I'm afraid the only reasonable course of action would be
> to (temporarily) revert the switch from yajl to jansson.
> 

Well, what if we linked with jansson statically? I'm not sure if it is
possible (and have no idea how to achieve that), but what if our dynamic
libraries we produce already contained jansson and thus linker would not
even try to resolve json_* symbols.

Michal