Re: [PATCH 2/3] drm/amd: validate user pitch alignment

2018-12-27 Thread Michel Dänzer 
On 2018-12-23 10:44 p.m., Yu Zhao wrote:
> On Fri, Dec 21, 2018 at 10:07:26AM +0100, Michel Dänzer wrote:
>> On 2018-12-21 4:10 a.m., Yu Zhao wrote:
>>> Userspace may request pitch alignment that is not supported by GPU.
>>> Some requests 32, but GPU ignores it and uses default 64 when cpp is
>>> 4. If GEM object is allocated based on the smaller alignment, GPU
>>> DMA will go out of bound.
>>>
>>> For GPU that does frame buffer compression, DMA writing out of bound
>>> memory will cause memory corruption.
>>>
>>> Signed-off-by: Yu Zhao 
>>> ---
>>>  drivers/gpu/drm/amd/amdgpu/amdgpu_display.c | 9 +
>>>  1 file changed, 9 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c 
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
>>> index e309d26170db..755daa332f8a 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
>>> @@ -527,6 +527,15 @@ amdgpu_display_user_framebuffer_create(struct 
>>> drm_device *dev,
>>> struct drm_gem_object *obj;
>>> struct amdgpu_framebuffer *amdgpu_fb;
>>> int ret;
>>> +   struct amdgpu_device *adev = dev->dev_private;
>>> +   int cpp = drm_format_plane_cpp(mode_cmd->pixel_format, 0);
>>> +   int pitch = amdgpu_align_pitch(adev, mode_cmd->width, cpp, false);
>>
>> Also, this needs to use mode_cmd->pitches[0] instead of mode_cmd->width,
>> otherwise it'll spuriously fail for larger but well-aligned pitches.
> 
> Actually mode_cmd->pitches[0] is aligned mode_cmd->width multiplied
> by cpp. So we can't just use mode_cmd->pitches[0].

Use mode_cmd->pitches[0] / cpp then?


> And I'm not sure if the hardware works with larger alignment

It does.

> (it certainly ignores smaller alignment).

Yeah, pitch must be >= width. Maybe this patch could check that as well.


-- 
Earthling Michel Dänzer   |   http://www.amd.com
Libre software enthusiast | Mesa and X developer

Re: [PATCH 2/3] drm/amd: validate user pitch alignment

2018-12-23 Thread Yu Zhao 
On Fri, Dec 21, 2018 at 10:07:26AM +0100, Michel Dänzer wrote:
> On 2018-12-21 4:10 a.m., Yu Zhao wrote:
> > Userspace may request pitch alignment that is not supported by GPU.
> > Some requests 32, but GPU ignores it and uses default 64 when cpp is
> > 4. If GEM object is allocated based on the smaller alignment, GPU
> > DMA will go out of bound.
> > 
> > For GPU that does frame buffer compression, DMA writing out of bound
> > memory will cause memory corruption.
> > 
> > Signed-off-by: Yu Zhao 
> > ---
> >  drivers/gpu/drm/amd/amdgpu/amdgpu_display.c | 9 +
> >  1 file changed, 9 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c 
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> > index e309d26170db..755daa332f8a 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> > @@ -527,6 +527,15 @@ amdgpu_display_user_framebuffer_create(struct 
> > drm_device *dev,
> > struct drm_gem_object *obj;
> > struct amdgpu_framebuffer *amdgpu_fb;
> > int ret;
> > +   struct amdgpu_device *adev = dev->dev_private;
> > +   int cpp = drm_format_plane_cpp(mode_cmd->pixel_format, 0);
> > +   int pitch = amdgpu_align_pitch(adev, mode_cmd->width, cpp, false);
> 
> Also, this needs to use mode_cmd->pitches[0] instead of mode_cmd->width,
> otherwise it'll spuriously fail for larger but well-aligned pitches.

Actually mode_cmd->pitches[0] is aligned mode_cmd->width multiplied
by cpp. So we can't just use mode_cmd->pitches[0]. And I'm not sure
if the hardware works with larger alignment (it certainly ignores
smaller alignment).

Re: [PATCH 2/3] drm/amd: validate user pitch alignment

2018-12-21 Thread Yu Zhao 
On Fri, Dec 21, 2018 at 10:07:26AM +0100, Michel Dänzer wrote:
> On 2018-12-21 4:10 a.m., Yu Zhao wrote:
> > Userspace may request pitch alignment that is not supported by GPU.
> > Some requests 32, but GPU ignores it and uses default 64 when cpp is
> > 4. If GEM object is allocated based on the smaller alignment, GPU
> > DMA will go out of bound.
> > 
> > For GPU that does frame buffer compression, DMA writing out of bound
> > memory will cause memory corruption.
> > 
> > Signed-off-by: Yu Zhao 
> > ---
> >  drivers/gpu/drm/amd/amdgpu/amdgpu_display.c | 9 +
> >  1 file changed, 9 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c 
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> > index e309d26170db..755daa332f8a 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> > @@ -527,6 +527,15 @@ amdgpu_display_user_framebuffer_create(struct 
> > drm_device *dev,
> > struct drm_gem_object *obj;
> > struct amdgpu_framebuffer *amdgpu_fb;
> > int ret;
> > +   struct amdgpu_device *adev = dev->dev_private;
> > +   int cpp = drm_format_plane_cpp(mode_cmd->pixel_format, 0);
> > +   int pitch = amdgpu_align_pitch(adev, mode_cmd->width, cpp, false);
> 
> Also, this needs to use mode_cmd->pitches[0] instead of mode_cmd->width,
> otherwise it'll spuriously fail for larger but well-aligned pitches.

Good point, thanks.

Re: [PATCH 2/3] drm/amd: validate user pitch alignment

2018-12-21 Thread Michel Dänzer 
On 2018-12-21 4:10 a.m., Yu Zhao wrote:
> Userspace may request pitch alignment that is not supported by GPU.
> Some requests 32, but GPU ignores it and uses default 64 when cpp is
> 4. If GEM object is allocated based on the smaller alignment, GPU
> DMA will go out of bound.
> 
> For GPU that does frame buffer compression, DMA writing out of bound
> memory will cause memory corruption.
> 
> Signed-off-by: Yu Zhao 
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_display.c | 9 +
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c 
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> index e309d26170db..755daa332f8a 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> @@ -527,6 +527,15 @@ amdgpu_display_user_framebuffer_create(struct drm_device 
> *dev,
>   struct drm_gem_object *obj;
>   struct amdgpu_framebuffer *amdgpu_fb;
>   int ret;
> + struct amdgpu_device *adev = dev->dev_private;
> + int cpp = drm_format_plane_cpp(mode_cmd->pixel_format, 0);
> + int pitch = amdgpu_align_pitch(adev, mode_cmd->width, cpp, false);

Also, this needs to use mode_cmd->pitches[0] instead of mode_cmd->width,
otherwise it'll spuriously fail for larger but well-aligned pitches.


-- 
Earthling Michel Dänzer   |   http://www.amd.com
Libre software enthusiast | Mesa and X developer

Re: [PATCH 2/3] drm/amd: validate user pitch alignment

2018-12-21 Thread Michel Dänzer 
On 2018-12-21 4:10 a.m., Yu Zhao wrote:
> Userspace may request pitch alignment that is not supported by GPU.
> Some requests 32, but GPU ignores it and uses default 64 when cpp is
> 4. If GEM object is allocated based on the smaller alignment, GPU
> DMA will go out of bound.
> 
> For GPU that does frame buffer compression, DMA writing out of bound
> memory will cause memory corruption.
> 
> Signed-off-by: Yu Zhao 
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_display.c | 9 +
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c 
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> index e309d26170db..755daa332f8a 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> @@ -527,6 +527,15 @@ amdgpu_display_user_framebuffer_create(struct drm_device 
> *dev,
>   struct drm_gem_object *obj;
>   struct amdgpu_framebuffer *amdgpu_fb;
>   int ret;
> + struct amdgpu_device *adev = dev->dev_private;
> + int cpp = drm_format_plane_cpp(mode_cmd->pixel_format, 0);
> + int pitch = amdgpu_align_pitch(adev, mode_cmd->width, cpp, false);
> +
> + if (mode_cmd->pitches[0] != pitch) {
> + dev_err(>pdev->dev, "Invalid pitch: expecting %d but got 
> %d\n",
> + pitch, mode_cmd->pitches[0]);

This message shouldn't be printed by default, or buggy / malicious
userspace can spam dmesg. I suggest using DRM_DEBUG_KMS or DRM_DEBUG_DRIVER.


> + return ERR_PTR(-EINVAL);
> + }
>  
>   obj = drm_gem_object_lookup(file_priv, mode_cmd->handles[0]);
>   if (obj ==  NULL) {
> 

Other than that, looks good to me.


-- 
Earthling Michel Dänzer   |   http://www.amd.com
Libre software enthusiast | Mesa and X developer

[PATCH 2/3] drm/amd: validate user pitch alignment

2018-12-20 Thread Yu Zhao 
Userspace may request pitch alignment that is not supported by GPU.
Some requests 32, but GPU ignores it and uses default 64 when cpp is
4. If GEM object is allocated based on the smaller alignment, GPU
DMA will go out of bound.

For GPU that does frame buffer compression, DMA writing out of bound
memory will cause memory corruption.

Signed-off-by: Yu Zhao 
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_display.c | 9 +
 1 file changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
index e309d26170db..755daa332f8a 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
@@ -527,6 +527,15 @@ amdgpu_display_user_framebuffer_create(struct drm_device 
*dev,
struct drm_gem_object *obj;
struct amdgpu_framebuffer *amdgpu_fb;
int ret;
+   struct amdgpu_device *adev = dev->dev_private;
+   int cpp = drm_format_plane_cpp(mode_cmd->pixel_format, 0);
+   int pitch = amdgpu_align_pitch(adev, mode_cmd->width, cpp, false);
+
+   if (mode_cmd->pitches[0] != pitch) {
+   dev_err(>pdev->dev, "Invalid pitch: expecting %d but got 
%d\n",
+   pitch, mode_cmd->pitches[0]);
+   return ERR_PTR(-EINVAL);
+   }
 
obj = drm_gem_object_lookup(file_priv, mode_cmd->handles[0]);
if (obj ==  NULL) {
-- 
2.20.1.415.g653613c723-goog