The error_report() call in drc_unisolate_logical() is not considering
that drc->dev->id can be NULL, and the underlying functions error_report()
calls to do its job (vprintf(), g_strdup_printf() ...) has undefined
behavior when trying to handle "%s" with NULL arguments.

Besides, there is no utility into reporting that an unknown device was
rejected by the guest.

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hw/ppc/spapr_drc.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/hw/ppc/spapr_drc.c b/hw/ppc/spapr_drc.c
index a2f2634601..a4d9496f76 100644
--- a/hw/ppc/spapr_drc.c
+++ b/hw/ppc/spapr_drc.c
@@ -167,8 +167,11 @@ static uint32_t drc_unisolate_logical(SpaprDrc *drc)
             }
 
             drc->unplug_requested = false;
-            error_report("Device hotunplug rejected by the guest "
-                         "for device %s", drc->dev->id);
+
+            if (drc->dev->id) {
+                error_report("Device hotunplug rejected by the guest "
+                             "for device %s", drc->dev->id);
+            }
 
             /*
              * TODO: send a QAPI DEVICE_UNPLUG_ERROR event when
-- 
2.31.1

On Mon, 12 Jul 2021 16:43:35 -0300
Daniel Henrique Barboza <danielhb413@gmail.com> wrote:

> The error_report() call in drc_unisolate_logical() is not considering
> that drc->dev->id can be NULL, and the underlying functions error_report()
> calls to do its job (vprintf(), g_strdup_printf() ...) has undefined
> behavior when trying to handle "%s" with NULL arguments.
> 
> Besides, there is no utility into reporting that an unknown device was
> rejected by the guest.
> 
> Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
> ---

Reviewed-by: Greg Kurz <groug@kaod.org>

>  hw/ppc/spapr_drc.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/ppc/spapr_drc.c b/hw/ppc/spapr_drc.c
> index a2f2634601..a4d9496f76 100644
> --- a/hw/ppc/spapr_drc.c
> +++ b/hw/ppc/spapr_drc.c
> @@ -167,8 +167,11 @@ static uint32_t drc_unisolate_logical(SpaprDrc *drc)
>              }
>  
>              drc->unplug_requested = false;
> -            error_report("Device hotunplug rejected by the guest "
> -                         "for device %s", drc->dev->id);
> +
> +            if (drc->dev->id) {
> +                error_report("Device hotunplug rejected by the guest "
> +                             "for device %s", drc->dev->id);
> +            }
>  
>              /*
>               * TODO: send a QAPI DEVICE_UNPLUG_ERROR event when