[Pkg-libvirt-maintainers] Bug#703208: Bug#703208: Bug#703208: libvirt0: segfault after upgrade from version 0.8.3-5+squeeze2 to 0.8.3-5+squeeze4

[Guido Günther]

On Sun, Mar 17, 2013 at 03:11:52PM +0100, Yves-Alexis Perez wrote:
> On dim., 2013-03-17 at 13:40 +0100, Salvatore Bonaccorso wrote:
> > Only now back. It looks like Guido already found the issue. But here
> > for reference the settings on the system where I saw this too (tough
> > in my case the VMs do not crash):
> > 
> > # ls -l /dev/kvm
> > crw-rw---- 1 root kvm 10, 232 Mar 11 06:47 /dev/kvm
> > # id libvirt-qemu
> > uid=108(libvirt-qemu) gid=112(kvm) groups=112(kvm),115(libvirt-qemu)
> > # getent group kvm
> > kvm:x:112:
> 
> I'm a bit puzzled. It looks like libvirt-qemu user should have
> permissions on kvm then.

Older libvirt (prior to 0.8.6) lack the proper initgroup calls. Without
these the process runs as libvirt-qemu:libvirt-qemu without any othter
group membership and therefore isn't allowed to access /dev/kvm.

That was the main motivation for using group kvm instead of separate
group in squeeze.

I vaguely remembered this when preparing the sec update and therefore
did extra testing but since the only kvm capable squeeze box around here
had a non standard setup (I need to test the stable as well as the
backports version on that one) this problem didn't show up and I didn't
check the code itself.

Cheers,
 -- Guido