[PATCH] drm/radeon:avoid null pointer dereference when dev is not bound

[bodefang]

I use static analysis tool to find these funcs are similar to the commit<0fa375e6bc90>(drm/rockchip: Fix suspend crash when drm is not bound),so it's just defensive, 
I haven't actually hitted this.







At 2021-01-05 01:00:27, "Alex Deucher" <alexdeucher at gmail.com> wrote:
>On Sun, Dec 27, 2020 at 3:56 PM Defang Bo <bodefang at 126.com> wrote:
>>
>> [Why]
>> Similar to commit<0fa375e6>. If the set_state/can_switch code access the drm_device when dev is not bound,
>> a null pointer dereference can happen.
>>
>> [How]
>> Add sanity checks to prevent it.
>>
>> Signed-off-by: Defang Bo <bodefang at 126.com>
>
>Are you actually hitting this or is this just defensive?  I don't
>think we can actually get into a state where this would be a problem.
>
>Alex
>
>> ---
>>  drivers/gpu/drm/radeon/radeon_device.c | 6 ++++++
>>  1 file changed, 6 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/radeon/radeon_device.c b/drivers/gpu/drm/radeon/radeon_device.c
>> index 266e3cb..50a1a60 100644
>> --- a/drivers/gpu/drm/radeon/radeon_device.c
>> +++ b/drivers/gpu/drm/radeon/radeon_device.c
>> @@ -1224,6 +1224,9 @@ static void radeon_switcheroo_set_state(struct pci_dev *pdev, enum vga_switchero
>>  {
>>         struct drm_device *dev = pci_get_drvdata(pdev);
>>
>> +       if (!dev)
>> +               return;
>> +
>>         if (radeon_is_px(dev) && state == VGA_SWITCHEROO_OFF)
>>                 return;
>>
>> @@ -1257,6 +1260,9 @@ static void radeon_switcheroo_set_state(struct pci_dev *pdev, enum vga_switchero
>>  static bool radeon_switcheroo_can_switch(struct pci_dev *pdev)
>>  {
>>         struct drm_device *dev = pci_get_drvdata(pdev);
>> +
>> +       if (!dev)
>> +               return false;
>>
>>         /*
>>          * FIXME: open_count is protected by drm_global_mutex but that would lead to
>> --
>> 2.7.4
>>
>> _______________________________________________
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>> amd-gfx at lists.freedesktop.org
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