drivers/gpu/drm/radeon/r600_blit.c: fix possible NULL pointer derefernce

[Alex Deucher]

On Tue, Jul 20, 2010 at 5:07 PM, Alexander Y. Fomichev
<git.user at gmail.com> wrote:
> On Wed, Jul 21, 2010 at 1:00 AM, Alex Deucher <alexdeucher at gmail.com> wrote:
>> On Tue, Jul 20, 2010 at 4:13 PM, Alexander Y. Fomichev
>> <git.user at gmail.com> wrote:
>>> On Tue, Jul 20, 2010 at 9:37 PM, Alex Deucher <alexdeucher at gmail.com> wrote:
>>>> On Mon, Jul 19, 2010 at 5:42 PM, Alexander Y. Fomichev
>>>> <git.user at gmail.com> wrote:
>>>>> This patch fix possible NULL pointer dereference when
>>>>> r600_prepare_blit_copy tries to fill dev_priv->blit_vb->file_priv
>>>>> without check of dev_priv->blit_vb. dev_priv->blit_vb should be
>>>>> filled by r600_nomm_get_vb but latest can fail with EAGAIN.
>>>>> Addresses: https://bugzilla.kernel.org/show_bug.cgi?id=16375
>>>>>
>>>>> ---
>>>>>  drivers/gpu/drm/radeon/r600_blit.c |    2 ++
>>>>>  1 files changed, 2 insertions(+), 0 deletions(-)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/radeon/r600_blit.c b/drivers/gpu/drm/radeon/r600_blit.c
>>>>> index f4fb88e..0df4a2b 100644
>>>>> --- a/drivers/gpu/drm/radeon/r600_blit.c
>>>>> +++ b/drivers/gpu/drm/radeon/r600_blit.c
>>>>> @@ -541,6 +541,8 @@ r600_prepare_blit_copy(struct drm_device *dev, struct drm_file *file_priv)
>>>>>        DRM_DEBUG("\n");
>>>>>
>>>>>        r600_nomm_get_vb(dev);
>>>>> +       if (!dev_priv->blit_vb)
>>>>> +               return;
>>>>
>>>> r600_prepare_blit_copy returns an int so something like this would be better:
>>>> --- a/drivers/gpu/drm/radeon/r600_blit.c
>>>> +++ b/drivers/gpu/drm/radeon/r600_blit.c
>>>> @@ -539,8 +539,10 @@ r600_prepare_blit_copy(struct drm_device *dev,
>>>> struct drm_file *file_priv)
>>>>  {
>>>>        drm_radeon_private_t *dev_priv = dev->dev_private;
>>>>        DRM_DEBUG("\n");
>>>> +       int ret = r600_nomm_get_vb(dev);
>>>>
>>>> -       r600_nomm_get_vb(dev);
>>>> +       if (ret)
>>>> +               return ret;
>>>>
>>>>        dev_priv->blit_vb->file_priv = file_priv;
>>>>
>>>>
>>>> Alex
>>>>
>>>>>
>>>>>        dev_priv->blit_vb->file_priv = file_priv;
>>>>>
>>>>> --
>>>>> 1.7.1.1
>>>>>
>>>>
>>>
>>> i haven't any preferneces, the only thing is - it would be logical
>>> to have every check in common style, so other cases
>>> (r600_blit_copy, r600_blit_swap) should be fixed, nop?
>>
>> Those are void functions so there's nothing to return.
>
> i mean both of them call r600_nomm_get_vb and both of them
> check if (!dev_priv->blit_vb), not return  value.I mean would be
> logical to check it the same way everytime r600_nomm_get_vb
> gets called.

yeah, either way.  You just need to return an error in r600_prepare_blit_copy.

Alex

>
>> Alex
>>
>>>
>>> --
>>> Best regards.
>>>        Alexander Y. Fomichev <git.user at gmail.com>
>>>
>>
>
>
>
> --
> Best regards.
>        Alexander Y. Fomichev <git.user at gmail.com>
>