[PATCH v2] drm/amdgpu: avoid using null object of framebuffer

[Huang Rui]

On Wed, Jun 19, 2024 at 12:46:25PM +0800, Huang Rui wrote:
> On Wed, Jun 19, 2024 at 12:29:24PM +0800, Zhang, Julia wrote:
> > Instead of using state->fb->obj[0] directly, get object from framebuffer
> > by calling drm_gem_fb_get_obj() and return error code when object is
> > null to avoid using null object of framebuffer.
> > 
> > v2: Call drm_gem_fb_get_obj after check old_state->fb for NULL.
> > 
> > Signed-off-by: Julia Zhang <Julia.Zhang at amd.com>
> > ---
> 
> Julia, you can add my RB during V1 in the next submission.
> 
> Reviewed-by: Huang Rui <ray.huang at amd.com>

CC Fusheng who reported the issue.

Fusheng, may we have your reported-by?

> 
> >  drivers/gpu/drm/amd/amdgpu/amdgpu_vkms.c | 18 ++++++++++++++++--
> >  1 file changed, 16 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vkms.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vkms.c
> > index d60c4a2eeb0c..212f6522859d 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vkms.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vkms.c
> > @@ -2,6 +2,7 @@
> >  
> >  #include <drm/drm_atomic_helper.h>
> >  #include <drm/drm_simple_kms_helper.h>
> > +#include <drm/drm_gem_framebuffer_helper.h>
> >  #include <drm/drm_vblank.h>
> >  
> >  #include "amdgpu.h"
> > @@ -311,7 +312,13 @@ static int amdgpu_vkms_prepare_fb(struct drm_plane *plane,
> >  		return 0;
> >  	}
> >  	afb = to_amdgpu_framebuffer(new_state->fb);
> > -	obj = new_state->fb->obj[0];
> > +
> > +	obj = drm_gem_fb_get_obj(new_state->fb, 0);
> > +	if (!obj) {
> > +		DRM_ERROR("Failed to get obj from framebuffer\n");
> > +		return -EINVAL;
> > +	}
> > +
> >  	rbo = gem_to_amdgpu_bo(obj);
> >  	adev = amdgpu_ttm_adev(rbo->tbo.bdev);
> >  
> > @@ -365,12 +372,19 @@ static void amdgpu_vkms_cleanup_fb(struct drm_plane *plane,
> >  				   struct drm_plane_state *old_state)
> >  {
> >  	struct amdgpu_bo *rbo;
> > +	struct drm_gem_object *obj;
> >  	int r;
> >  
> >  	if (!old_state->fb)
> >  		return;
> >  
> > -	rbo = gem_to_amdgpu_bo(old_state->fb->obj[0]);
> > +	obj = drm_gem_fb_get_obj(old_state->fb, 0);
> > +	if (!obj) {
> > +		DRM_ERROR("Failed to get obj from framebuffer\n");
> > +		return;
> > +	}
> > +
> > +	rbo = gem_to_amdgpu_bo(obj);
> >  	r = amdgpu_bo_reserve(rbo, false);
> >  	if (unlikely(r)) {
> >  		DRM_ERROR("failed to reserve rbo before unpin\n");
> > -- 
> > 2.34.1
> >