Re: [Qemu-devel] [PATCH v2] migrate: Introduce a 'dc->vmsd' check to avoid segfault for --only-migratable

[Paolo Bonzini]

On 04/02/2017 00:59, Ashijeet Acharya wrote:
> Commit a3a3d8c7 introduced a segfault bug while checking for
> 'dc->vmsd->unmigratable' which caused QEMU to crash when trying to add
> devices which do no set their 'dc->vmsd' yet while initialization.
> Place a 'dc->vmsd' check prior to it so that we do not segfault for
> such devices.
> 
> NOTE: This doesn't compromise the functioning of --only-migratable
> option as all the unmigratable devices do set their 'dc->vmsd'.
> 
> Signed-off-by: Ashijeet Acharya 
> Reviewed-by: Juan Quintela 
> ---
> Changes in v2:
> - place dc->vmsd check in hw/usb/bus.c as well
> ---
>  hw/usb/bus.c   | 2 +-
>  qdev-monitor.c | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/usb/bus.c b/hw/usb/bus.c
> index 1dcc35c..1e39b2c 100644
> --- a/hw/usb/bus.c
> +++ b/hw/usb/bus.c
> @@ -731,7 +731,7 @@ USBDevice *usbdevice_create(const char *cmdline)
>  
>  dc = DEVICE_CLASS(klass);
>  
> -if (only_migratable) {
> +if (only_migratable && dc->vmsd) {
>  if (dc->vmsd->unmigratable) {
>  error_report("Device %s is not migratable, but --only-migratable 
> "
>   "was specified", f->name);
> diff --git a/qdev-monitor.c b/qdev-monitor.c
> index 549f45f..b72e5a4 100644
> --- a/qdev-monitor.c
> +++ b/qdev-monitor.c
> @@ -579,7 +579,7 @@ DeviceState *qdev_device_add(QemuOpts *opts, Error **errp)
>  return NULL;
>  }
>  
> -if (only_migratable) {
> +if (only_migratable && dc->vmsd) {
>  if (dc->vmsd->unmigratable) {
>  error_setg(errp, "Device %s is not migratable, but "
> "--only-migratable was specified", driver);
> 

Could you handle only_migratable in device_set_realized (inside "if
(value && !dev->realized)"), to avoid the code duplication?  Separate
patch from this one, of course.

Thanks,

Paolo

[Qemu-devel] [PATCH v2] migrate: Introduce a 'dc->vmsd' check to avoid segfault for --only-migratable

[Ashijeet Acharya]

Commit a3a3d8c7 introduced a segfault bug while checking for
'dc->vmsd->unmigratable' which caused QEMU to crash when trying to add
devices which do no set their 'dc->vmsd' yet while initialization.
Place a 'dc->vmsd' check prior to it so that we do not segfault for
such devices.

NOTE: This doesn't compromise the functioning of --only-migratable
option as all the unmigratable devices do set their 'dc->vmsd'.

Signed-off-by: Ashijeet Acharya 
Reviewed-by: Juan Quintela 
---
Changes in v2:
- place dc->vmsd check in hw/usb/bus.c as well
---
 hw/usb/bus.c   | 2 +-
 qdev-monitor.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/hw/usb/bus.c b/hw/usb/bus.c
index 1dcc35c..1e39b2c 100644
--- a/hw/usb/bus.c
+++ b/hw/usb/bus.c
@@ -731,7 +731,7 @@ USBDevice *usbdevice_create(const char *cmdline)
 
 dc = DEVICE_CLASS(klass);
 
-if (only_migratable) {
+if (only_migratable && dc->vmsd) {
 if (dc->vmsd->unmigratable) {
 error_report("Device %s is not migratable, but --only-migratable "
  "was specified", f->name);
diff --git a/qdev-monitor.c b/qdev-monitor.c
index 549f45f..b72e5a4 100644
--- a/qdev-monitor.c
+++ b/qdev-monitor.c
@@ -579,7 +579,7 @@ DeviceState *qdev_device_add(QemuOpts *opts, Error **errp)
 return NULL;
 }
 
-if (only_migratable) {
+if (only_migratable && dc->vmsd) {
 if (dc->vmsd->unmigratable) {
 error_setg(errp, "Device %s is not migratable, but "
"--only-migratable was specified", driver);
-- 
2.6.2