On Thu, Sep 21, 2017 at 12:21 AM, Erik Skultety <eskul...@redhat.com> wrote:
> On Wed, Sep 20, 2017 at 12:19:16PM -0700, ashish mittal wrote:
> > On Wed, Sep 20, 2017 at 6:11 AM, Erik Skultety <eskul...@redhat.com>
> wrote:
> >
> > > On Wed, Sep 20, 2017 at 05:32:29AM -0700, Ashish Mittal wrote:
> > > > Passing a NULL value for the argument secAlias to the function
> > > > qemuDomainGetTLSObjects would cause a segmentation fault in
> > > > libvirtd.
> > > >
> > > > Changed code to not dereference a NULL secAlias.
> > > >
> > > > Signed-off-by: Ashish Mittal <ashmit...@gmail.com>
> > > > ---
> > > > src/qemu/qemu_hotplug.c | 3 ++-
> > > > 1 file changed, 2 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
> > > > index 7dd6e5f..9ecdf0a 100644
> > > > --- a/src/qemu/qemu_hotplug.c
> > > > +++ b/src/qemu/qemu_hotplug.c
> > > > @@ -1643,7 +1643,8 @@ qemuDomainGetTLSObjects(virQEMUCapsPtr
> qemuCaps,
> > > > }
> > > >
> > > > if (qemuBuildTLSx509BackendProps(tlsCertdir, tlsListen,
> tlsVerify,
> > > > - *secAlias, qemuCaps, tlsProps)
> < 0)
> > > > + secAlias ? *secAlias : NULL,
> > > qemuCaps,
> > > > + tlsProps) < 0)
> > > > return -1;
> > > >
> > > > if (!(*tlsAlias = qemuAliasTLSObjFromSrcAlias(srcAlias)))
> > >
> > > A few lines above this context, we check whether we have a valid
> reference
> > > to
> > > @secinfo and if so, we try to fill the @secAlias. Can we guarantee that
> > > when
> > > @secinfo is passed, @secAlias has been set as well?
> >
> >
> > When secinfo is passed, the line marked below should guarantee that
> > secAlias is set to not-null.
> >
> > if (secinfo) {
> > if (qemuBuildSecretInfoProps(secinfo, secProps) < 0)
> > return -1;
> >
> > if (!(*secAlias = qemuDomainGetSecretAESAlias(srcAlias, false)))
> > <=== this should ensure secAlias != NULL or return -1
> > return -1;
> > }
> >
>
> See John's reply to my response, long story short, in case of Veritas, this
> couldn't happen, but in general, we should cover the use case I'm
> describing as
> well, which is just a matter of very simple 'if' statement adjustment.
>
> Erik
>
if (secinfo) {
if (qemuBuildSecretInfoProps(secinfo, secProps) < 0)
return -1;
if (!(*secAlias = qemuDomainGetSecretAESAlias(srcAlias, false)))
return -1;
}
Above code segment suggests that if secinfo != NULL, then secAlias should
never be NULL . If that were not the case, we would have already seen a
crash from such a case.
I'm afraid changing the above "if" condition to "if (secinfo && secAlias)"
is changing the behavior of the code to say "It is OK if secinfo != NULL
and secAlias == NULL, I'll just skip the setting of *secAlias". I don't
know the code well enough to say if this, or the above, is expected
behavior. If the expected behavior is that secAlias should never be NULL
when secinfo != NULL, then a safer change might be -
if (secinfo) {
if (!secAlias)
return -1;
....
Regards,
Ashish
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