Re: [Qemu-devel] [PATCH 2/3] hw/s390x: fix memory leak in s390_init_ipl_dev()

[Greg Kurz <groug@kaod.org>]

On Thu, 29 Mar 2018 11:27:21 +0200
Igor Mammedov <imammedo@redhat.com> wrote:

> On Thu, 29 Mar 2018 11:10:06 +0200
> Greg Kurz <groug@kaod.org> wrote:
> 
> > The string returned by object_property_get_str() is dynamically allocated.
> > 
> > Fixes: 3c4e9baacf4d9
> > Signed-off-by: Greg Kurz <groug@kaod.org>
> > ---
> >  hw/s390x/s390-virtio-ccw.c |    5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
> > index 864145a7c6f3..435f7c99e77c 100644
> > --- a/hw/s390x/s390-virtio-ccw.c
> > +++ b/hw/s390x/s390-virtio-ccw.c
> > @@ -246,6 +246,7 @@ static void s390_init_ipl_dev(const char *kernel_filename,
> >  {
> >      Object *new = object_new(TYPE_S390_IPL);
> >      DeviceState *dev = DEVICE(new);
> > +    char *netboot_fw_prop;
> >  
> >      if (kernel_filename) {
> >          qdev_prop_set_string(dev, "kernel", kernel_filename);
> > @@ -256,9 +257,11 @@ static void s390_init_ipl_dev(const char *kernel_filename,
> >      qdev_prop_set_string(dev, "cmdline", kernel_cmdline);
> >      qdev_prop_set_string(dev, "firmware", firmware);
> >      qdev_prop_set_bit(dev, "enforce_bios", enforce_bios);
> > -    if (!strlen(object_property_get_str(new, "netboot_fw", &error_abort))) {
> > +    netboot_fw_prop = object_property_get_str(new, "netboot_fw", &error_abort);
> > +    if (!strlen(netboot_fw_prop)) {  
> probably not really issue here but,
> is strlen really safe in case netboot_fw_prop == NULL?
> 

You're right, object_property_get_str() can theoretically return NULL and
strlen() would crash... Not sure how this would happen though. Anyway, the
current code doesn't check if object_property_get_str() returns NULL so
if this needs to be fixed as well, let's do it in a followup patch.

> >          qdev_prop_set_string(dev, "netboot_fw", netboot_fw);
> >      }
> > +    g_free(netboot_fw_prop);
> >      object_property_add_child(qdev_get_machine(), TYPE_S390_IPL,
> >                                new, NULL);
> >      object_unref(new);
> > 
> >   
>