re: acer-wmi: fix obj is NULL but dereferenced

[joeyli <jlee@suse.com>]

Hi Dan, 

Sorry for I am late to reply you!

於 一，2013-01-07 於 14:32 +0300，Dan Carpenter 提到：
> Hello Lee, Chun-Yi,
> 
> The patch 727651bf738b: "acer-wmi: fix obj is NULL but dereferenced" 
> from Dec 14, 2012, leads to the following warning:
> drivers/platform/x86/acer-wmi.c:1227 WMID_set_capabilities()
> 	 warn: calling kfree() when 'out.pointer' is always NULL.
> 
>   1217          obj = (union acpi_object *) out.pointer;
>   1218          if (obj) {
>   1219                  if (obj->type == ACPI_TYPE_BUFFER &&
>   1220                          (obj->buffer.length == sizeof(u32) ||
>   1221                          obj->buffer.length == sizeof(u64))) {
>   1222                          devices = *((u32 *) obj->buffer.pointer);
>   1223                  } else if (obj->type == ACPI_TYPE_INTEGER) {
>   1224                          devices = (u32) obj->integer.value;
>   1225                  }
>   1226          } else {
>   1227                  kfree(out.pointer);
>   1228                  return AE_ERROR;
>   1229          }
> 
> I was going to remove the kfree() but looking the patch which introduced
> it causes GCC warnings and so there is some other stuff which needs to
> be fixed as well.
> 
> regards,
> dan carpenter
> 
> 

The warning will be fixed by Zhang Rui or Paul Bolle's patch:

http://www.mail-archive.com/platform-driver-x86@vger.kernel.org/msg04016.html
http://lkml.org/lkml/2013/1/24/215

With the above patch, kfree() will called when:
 + obj is not NULL but the type is not BUFFER or INTEGER
or
 + obj is NULL. The kfree() check obj is NULL then direct return.

Still appreciate for your review and suggestion!


Thanks a lot!
Joey Lee