Patchwork [v1,1/1] qom: Fix class cast of NULL classes

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Submitter Peter Crosthwaite
Date June 18, 2013, 9:18 a.m.
Message ID <94cd5ba46b74eea289a7e582635820c1c54e66fa.1371546907.git.peter.crosthwaite@xilinx.com>
Download mbox | patch
Permalink /patch/252193/
State New
Headers show

Comments

Peter Crosthwaite - June 18, 2013, 9:18 a.m.
From: Peter Crosthwaite <peter.crosthwaite@xilinx.com>

Its clear from the implementation that class casting is supposed to work
with a NULL class argument. Guard all dereferences of the class argument
against NULL accordingly.

Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
---

 qom/object.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
Paolo Bonzini - June 18, 2013, 9:53 a.m.
Il 18/06/2013 11:18, peter.crosthwaite@xilinx.com ha scritto:
> From: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
> 
> Its clear from the implementation that class casting is supposed to work
> with a NULL class argument. Guard all dereferences of the class argument
> against NULL accordingly.
> 
> Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>

Cc: qemu-stable@nongnu.org


> ---
> 
>  qom/object.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/qom/object.c b/qom/object.c
> index 803b94b..b7ecb9f 100644
> --- a/qom/object.c
> +++ b/qom/object.c
> @@ -531,14 +531,14 @@ ObjectClass *object_class_dynamic_cast_assert(ObjectClass *class,
>  #ifdef CONFIG_QOM_CAST_DEBUG
>      int i;
>  
> -    for (i = 0; i < OBJECT_CLASS_CAST_CACHE; i++) {
> +    for (i = 0; class && i < OBJECT_CLASS_CAST_CACHE; i++) {
>          if (class->cast_cache[i] == typename) {
>              ret = class;
>              goto out;
>          }
>      }
>  #else
> -    if (!class->interfaces) {
> +    if (!class || !class->interfaces) {
>          return class;
>      }
>  #endif
> @@ -551,7 +551,7 @@ ObjectClass *object_class_dynamic_cast_assert(ObjectClass *class,
>      }
>  
>  #ifdef CONFIG_QOM_CAST_DEBUG
> -    if (ret == class) {
> +    if (class && ret == class) {
>          for (i = 1; i < OBJECT_CLASS_CAST_CACHE; i++) {
>              class->cast_cache[i - 1] = class->cast_cache[i];
>          }
>
Peter Crosthwaite - July 10, 2013, 5:17 a.m.
Ping!

On Tue, Jun 18, 2013 at 7:18 PM,  <peter.crosthwaite@xilinx.com> wrote:
> From: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
>
> Its clear from the implementation that class casting is supposed to work
> with a NULL class argument. Guard all dereferences of the class argument
> against NULL accordingly.
>
> Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
> ---
>
>  qom/object.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/qom/object.c b/qom/object.c
> index 803b94b..b7ecb9f 100644
> --- a/qom/object.c
> +++ b/qom/object.c
> @@ -531,14 +531,14 @@ ObjectClass *object_class_dynamic_cast_assert(ObjectClass *class,
>  #ifdef CONFIG_QOM_CAST_DEBUG
>      int i;
>
> -    for (i = 0; i < OBJECT_CLASS_CAST_CACHE; i++) {
> +    for (i = 0; class && i < OBJECT_CLASS_CAST_CACHE; i++) {
>          if (class->cast_cache[i] == typename) {
>              ret = class;
>              goto out;
>          }
>      }
>  #else
> -    if (!class->interfaces) {
> +    if (!class || !class->interfaces) {
>          return class;
>      }
>  #endif
> @@ -551,7 +551,7 @@ ObjectClass *object_class_dynamic_cast_assert(ObjectClass *class,
>      }
>
>  #ifdef CONFIG_QOM_CAST_DEBUG
> -    if (ret == class) {
> +    if (class && ret == class) {
>          for (i = 1; i < OBJECT_CLASS_CAST_CACHE; i++) {
>              class->cast_cache[i - 1] = class->cast_cache[i];
>          }
> --
> 1.8.3.rc1.44.gb387c77.dirty
>
Anthony Liguori - July 10, 2013, 7:33 p.m.
Applied.  Thanks.

Regards,

Anthony Liguori

Patch

diff --git a/qom/object.c b/qom/object.c
index 803b94b..b7ecb9f 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -531,14 +531,14 @@  ObjectClass *object_class_dynamic_cast_assert(ObjectClass *class,
 #ifdef CONFIG_QOM_CAST_DEBUG
     int i;
 
-    for (i = 0; i < OBJECT_CLASS_CAST_CACHE; i++) {
+    for (i = 0; class && i < OBJECT_CLASS_CAST_CACHE; i++) {
         if (class->cast_cache[i] == typename) {
             ret = class;
             goto out;
         }
     }
 #else
-    if (!class->interfaces) {
+    if (!class || !class->interfaces) {
         return class;
     }
 #endif
@@ -551,7 +551,7 @@  ObjectClass *object_class_dynamic_cast_assert(ObjectClass *class,
     }
 
 #ifdef CONFIG_QOM_CAST_DEBUG
-    if (ret == class) {
+    if (class && ret == class) {
         for (i = 1; i < OBJECT_CLASS_CAST_CACHE; i++) {
             class->cast_cache[i - 1] = class->cast_cache[i];
         }