[libvirt] [PATCH] Fix libvirtd crash in qemuDomainGetTLSObjects

[Erik Skultety]

On Tue, Sep 19, 2017 at 09:58:34PM -0700, Ashish Mittal wrote:
> Passing a NULL value for the argument secAlias to the function
> qemuDomainGetTLSObjects causes a segmentation fault.
>
> Thread 3 "libvirtd" received signal SIGSEGV, Segmentation fault.
> 0x00007f97c9c42a3d in qemuDomainGetTLSObjects (...,secAlias=0x0)
> at qemu/qemu_hotplug.c:1736

Can you provide the whole backtrace? Because from what I see in the code,
qemuDomainGetTLSObjects is called from qemu_hotplug.c and qemu_migration.c, but
none of the code paths would result in qemuDomainGetTLSObjects to get secAlias
== NULL, solely because all the callers (direct or indirect) of this method call
it as &secAlias. Therefore, I think the case you're trying to fix cannot
happen in the current state - the fix is also wrong, see below.


>
>      if (qemuBuildTLSx509BackendProps(tlsCertdir, tlsListen, tlsVerify,
> -                                     *secAlias, qemuCaps, tlsProps) < 0)
> +                                     **secAlias ? *secAlias : NULL, qemuCaps,

So, hypothetically, if secAlias == NULL and *secAlias results in a SEGFAULT,
what is the result of doing **secAlias? Correct, a SEGFAULT.

Erik