Re: [v4 5/5] drm/amdgpu: fix invalid memory access in amdgpu_fence_driver_sw_fini()

["Christian König" <christian.koenig@amd.com>]

Am 10.01.25 um 03:08 schrieb Jiang Liu:
> Function detects initialization status by checking sched->ops, so set
> sched->ops to non-NULL just before return in function
> amdgpu_fence_driver_sw_fini() and amdgpu_device_init_schedulers()
> to avoid possible invalid memory access on error recover path.
>
> Signed-off-by: Jiang Liu <gerry@linux.alibaba.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 1 +
>   drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c  | 4 +++-
>   2 files changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index f29a4ad3c6d0..3688e9eb949b 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -2857,6 +2857,7 @@ static int amdgpu_device_init_schedulers(struct amdgpu_device *adev)
>   		if (r) {
>   			DRM_ERROR("Failed to create scheduler on ring %s.\n",
>   				  ring->name);
> +			ring->sched.ops = NULL;
>   			return r;
>   		}
>   		r = amdgpu_uvd_entity_init(adev, ring);
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
> index 2f24a6aa13bf..b5e87b515139 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c
> @@ -656,8 +656,10 @@ void amdgpu_fence_driver_sw_fini(struct amdgpu_device *adev)
>   		 * The natural check would be sched.ready, which is
>   		 * set as drm_sched_init() finishes...
>   		 */
> -		if (ring->sched.ops)
> +		if (ring->sched.ops) {
>   			drm_sched_fini(&ring->sched);
> +			ring->sched.ops = NULL;
> +		}

As said in my previous reply we should really stop checking sched.ops here.

The scheduler should not be cleaned up by this function in the first place.

Regards,
Christian.

>   
>   		for (j = 0; j <= ring->fence_drv.num_fences_mask; ++j)
>   			dma_fence_put(ring->fence_drv.fences[j]);