[v2] pc: fix possible NULL pointer dereference in pc_machine_get_device_memory_region_size()

[Qemu-devel] [PATCH v2] pc: fix possible NULL pointer dereference in pc_machine_get_device_memory_region_size()

Posted by Igor Mammedov 6 years, 7 months ago

QEMU will crash when device-memory-region-size property is read if ms->device_memory
wasn't initialized yet.

Crash can be reproduced with:
 $QEMU -preconfig -qmp unix:qmp_socket,server,nowait &
 ./scripts/qmp/qom-get -s qmp_socket /machine.device-memory-region-size

Instead of crashing return 0 if ms->device_memory hasn't been initialized.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---

v2:
  * fix missing return value assignment
      (Eduardo Habkost <ehabkost@redhat.com>)
---
 hw/i386/pc.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index e96360b47a..552f3401e2 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -2458,7 +2458,11 @@ pc_machine_get_device_memory_region_size(Object *obj, Visitor *v,
                                          Error **errp)
 {
     MachineState *ms = MACHINE(obj);
-    int64_t value = memory_region_size(&ms->device_memory->mr);
+    int64_t value = 0;
+
+    if (ms->device_memory) {
+        value = memory_region_size(&ms->device_memory->mr);
+    }
 
     visit_type_int(v, name, &value, errp);
 }
-- 
2.18.1

Re: [Qemu-devel] [PATCH v2] pc: fix possible NULL pointer dereference in pc_machine_get_device_memory_region_size()

Posted by Philippe Mathieu-Daudé 6 years, 7 months ago

On 6/24/19 11:02 AM, Igor Mammedov wrote:
> QEMU will crash when device-memory-region-size property is read if ms->device_memory
> wasn't initialized yet.
> 
> Crash can be reproduced with:
>  $QEMU -preconfig -qmp unix:qmp_socket,server,nowait &
>  ./scripts/qmp/qom-get -s qmp_socket /machine.device-memory-region-size
> 
> Instead of crashing return 0 if ms->device_memory hasn't been initialized.
> 
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

> ---
> 
> v2:
>   * fix missing return value assignment
>       (Eduardo Habkost <ehabkost@redhat.com>)
> ---
>  hw/i386/pc.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index e96360b47a..552f3401e2 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -2458,7 +2458,11 @@ pc_machine_get_device_memory_region_size(Object *obj, Visitor *v,
>                                           Error **errp)
>  {
>      MachineState *ms = MACHINE(obj);
> -    int64_t value = memory_region_size(&ms->device_memory->mr);
> +    int64_t value = 0;
> +
> +    if (ms->device_memory) {
> +        value = memory_region_size(&ms->device_memory->mr);
> +    }
>  
>      visit_type_int(v, name, &value, errp);
>  }
>

Re: [Qemu-devel] [PATCH v2] pc: fix possible NULL pointer dereference in pc_machine_get_device_memory_region_size()

Posted by Michael S. Tsirkin 6 years, 6 months ago

On Mon, Jun 24, 2019 at 05:02:00AM -0400, Igor Mammedov wrote:
> QEMU will crash when device-memory-region-size property is read if ms->device_memory
> wasn't initialized yet.
> 
> Crash can be reproduced with:
>  $QEMU -preconfig -qmp unix:qmp_socket,server,nowait &
>  ./scripts/qmp/qom-get -s qmp_socket /machine.device-memory-region-size
> 
> Instead of crashing return 0 if ms->device_memory hasn't been initialized.
> 
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>

queued, thanks!

> ---
> 
> v2:
>   * fix missing return value assignment
>       (Eduardo Habkost <ehabkost@redhat.com>)
> ---
>  hw/i386/pc.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index e96360b47a..552f3401e2 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -2458,7 +2458,11 @@ pc_machine_get_device_memory_region_size(Object *obj, Visitor *v,
>                                           Error **errp)
>  {
>      MachineState *ms = MACHINE(obj);
> -    int64_t value = memory_region_size(&ms->device_memory->mr);
> +    int64_t value = 0;
> +
> +    if (ms->device_memory) {
> +        value = memory_region_size(&ms->device_memory->mr);
> +    }
>  
>      visit_type_int(v, name, &value, errp);
>  }
> -- 
> 2.18.1

Re: [Qemu-devel] [PATCH v2] pc: fix possible NULL pointer dereference in pc_machine_get_device_memory_region_size()

Posted by Paolo Bonzini 6 years, 6 months ago

On 17/07/19 12:37, Michael S. Tsirkin wrote:
> On Mon, Jun 24, 2019 at 05:02:00AM -0400, Igor Mammedov wrote:
>> QEMU will crash when device-memory-region-size property is read if ms->device_memory
>> wasn't initialized yet.
>>
>> Crash can be reproduced with:
>>  $QEMU -preconfig -qmp unix:qmp_socket,server,nowait &
>>  ./scripts/qmp/qom-get -s qmp_socket /machine.device-memory-region-size
>>
>> Instead of crashing return 0 if ms->device_memory hasn't been initialized.
>>
>> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> 
> queued, thanks!

This is already commit 58164eaff530a1e804f5710936dd37518ab5a90e.

Paolo

Re: [Qemu-devel] [PATCH v2] pc: fix possible NULL pointer dereference in pc_machine_get_device_memory_region_size()

Posted by Michael S. Tsirkin 6 years, 6 months ago

On Wed, Jul 17, 2019 at 01:22:27PM +0200, Paolo Bonzini wrote:
> On 17/07/19 12:37, Michael S. Tsirkin wrote:
> > On Mon, Jun 24, 2019 at 05:02:00AM -0400, Igor Mammedov wrote:
> >> QEMU will crash when device-memory-region-size property is read if ms->device_memory
> >> wasn't initialized yet.
> >>
> >> Crash can be reproduced with:
> >>  $QEMU -preconfig -qmp unix:qmp_socket,server,nowait &
> >>  ./scripts/qmp/qom-get -s qmp_socket /machine.device-memory-region-size
> >>
> >> Instead of crashing return 0 if ms->device_memory hasn't been initialized.
> >>
> >> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> > 
> > queued, thanks!
> 
> This is already commit 58164eaff530a1e804f5710936dd37518ab5a90e.
> 
> Paolo

In fact yes, git am just silently ignores a patch.
Donnu why did it not get dropped from the review inbox, weird.

Thanks!

-- 
MST