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

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

[Defang Bo]

[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@126.com>
---
 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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Re: [PATCH] drm/radeon:avoid null pointer dereference when dev is not bound

[Alex Deucher]

On Sun, Dec 27, 2020 at 3:56 PM Defang Bo <bodefang@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@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
>
> _______________________________________________
> amd-gfx mailing list
> amd-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/amd-gfx
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Re:Re: [PATCH] drm/radeon:avoid null pointer dereference when dev is not bound

[bodefang]

[-- Attachment #1.1: Type: text/plain, Size: 1990 bytes --]

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@gmail.com> wrote:
>On Sun, Dec 27, 2020 at 3:56 PM Defang Bo <bodefang@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@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
>>
>> _______________________________________________
>> amd-gfx mailing list
>> amd-gfx@lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/amd-gfx

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