[PATCH] drm/amdgpu: fix a bug NULL pointer dereference

[Christian König]

Well of hand this patch looks like a clear NAK to me.

Returning without raising an error is certainly the wrong thing to do 
here because we just drop the necessary page table updates.

How does the entity->rq ends up as NULL in the first place?

Regards,
Christian.

Am 19.02.20 um 07:26 schrieb Zhang, Hawking:
> [AMD Official Use Only - Internal Distribution Only]
>
> Reviewed-by: Hawking Zhang <Hawking.Zhang at amd.com>
>
> Regards,
> Hawking
> -----Original Message-----
> From: Dennis Li <Dennis.Li at amd.com>
> Sent: Wednesday, February 19, 2020 12:05
> To: amd-gfx at lists.freedesktop.org; Deucher, Alexander <Alexander.Deucher at amd.com>; Zhou1, Tao <Tao.Zhou1 at amd.com>; Zhang, Hawking <Hawking.Zhang at amd.com>; Chen, Guchun <Guchun.Chen at amd.com>
> Cc: Li, Dennis <Dennis.Li at amd.com>
> Subject: [PATCH] drm/amdgpu: fix a bug NULL pointer dereference
>
> check whether the queue of entity is null to avoid null pointer dereference.
>
> Change-Id: I08d56774012cf229ba2fe7a011c1359e8d1e2781
> Signed-off-by: Dennis Li <Dennis.Li at amd.com>
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c
> index 4cc7881f438c..67cca463ddcc 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c
> @@ -95,6 +95,9 @@ static int amdgpu_vm_sdma_commit(struct amdgpu_vm_update_params *p,
>   	int r;
>   
>   	entity = p->direct ? &p->vm->direct : &p->vm->delayed;
> +	if (!entity->rq)
> +		return 0;
> +
>   	ring = container_of(entity->rq->sched, struct amdgpu_ring, sched);
>   
>   	WARN_ON(ib->length_dw == 0);
> --
> 2.17.1
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