[PATCH 2/4] drm/panthor: Keep a ref to the VM at the panthor_kernel_bo level

Liviu Dudau liviu.dudau at arm.com
Fri May 3 11:46:48 UTC 2024


On Thu, May 02, 2024 at 08:38:10PM +0200, Boris Brezillon wrote:
> Avoids use-after-free situations when panthor_fw_unplug() is called
> and the kernel BO was mapped to the FW VM.
> 
> Signed-off-by: Boris Brezillon <boris.brezillon at collabora.com>

Reviewed-by: Liviu Dudau <liviu.dudau at arm.com>

> ---
>  drivers/gpu/drm/panthor/panthor_fw.c    |  4 ++--
>  drivers/gpu/drm/panthor/panthor_gem.c   |  8 +++++---
>  drivers/gpu/drm/panthor/panthor_gem.h   |  8 ++++++--
>  drivers/gpu/drm/panthor/panthor_heap.c  |  8 ++++----
>  drivers/gpu/drm/panthor/panthor_sched.c | 11 +++++------
>  5 files changed, 22 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
> index 181395e2859a..b41685304a83 100644
> --- a/drivers/gpu/drm/panthor/panthor_fw.c
> +++ b/drivers/gpu/drm/panthor/panthor_fw.c
> @@ -453,7 +453,7 @@ panthor_fw_alloc_queue_iface_mem(struct panthor_device *ptdev,
>  
>  	ret = panthor_kernel_bo_vmap(mem);
>  	if (ret) {
> -		panthor_kernel_bo_destroy(panthor_fw_vm(ptdev), mem);
> +		panthor_kernel_bo_destroy(mem);
>  		return ERR_PTR(ret);
>  	}
>  
> @@ -1133,7 +1133,7 @@ void panthor_fw_unplug(struct panthor_device *ptdev)
>  	panthor_fw_stop(ptdev);
>  
>  	list_for_each_entry(section, &ptdev->fw->sections, node)
> -		panthor_kernel_bo_destroy(panthor_fw_vm(ptdev), section->mem);
> +		panthor_kernel_bo_destroy(section->mem);
>  
>  	/* We intentionally don't call panthor_vm_idle() and let
>  	 * panthor_mmu_unplug() release the AS we acquired with
> diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/drm/panthor/panthor_gem.c
> index d6483266d0c2..38f560864879 100644
> --- a/drivers/gpu/drm/panthor/panthor_gem.c
> +++ b/drivers/gpu/drm/panthor/panthor_gem.c
> @@ -26,18 +26,18 @@ static void panthor_gem_free_object(struct drm_gem_object *obj)
>  
>  /**
>   * panthor_kernel_bo_destroy() - Destroy a kernel buffer object
> - * @vm: The VM this BO was mapped to.
>   * @bo: Kernel buffer object to destroy. If NULL or an ERR_PTR(), the destruction
>   * is skipped.
>   */
> -void panthor_kernel_bo_destroy(struct panthor_vm *vm,
> -			       struct panthor_kernel_bo *bo)
> +void panthor_kernel_bo_destroy(struct panthor_kernel_bo *bo)
>  {
> +	struct panthor_vm *vm;
>  	int ret;
>  
>  	if (IS_ERR_OR_NULL(bo))
>  		return;
>  
> +	vm = bo->vm;
>  	panthor_kernel_bo_vunmap(bo);
>  
>  	if (drm_WARN_ON(bo->obj->dev,
> @@ -53,6 +53,7 @@ void panthor_kernel_bo_destroy(struct panthor_vm *vm,
>  	drm_gem_object_put(bo->obj);
>  
>  out_free_bo:
> +	panthor_vm_put(vm);
>  	kfree(bo);
>  }
>  
> @@ -106,6 +107,7 @@ panthor_kernel_bo_create(struct panthor_device *ptdev, struct panthor_vm *vm,
>  	if (ret)
>  		goto err_free_va;
>  
> +	kbo->vm = panthor_vm_get(vm);
>  	bo->exclusive_vm_root_gem = panthor_vm_root_gem(vm);
>  	drm_gem_object_get(bo->exclusive_vm_root_gem);
>  	bo->base.base.resv = bo->exclusive_vm_root_gem->resv;
> diff --git a/drivers/gpu/drm/panthor/panthor_gem.h b/drivers/gpu/drm/panthor/panthor_gem.h
> index 3bccba394d00..e43021cf6d45 100644
> --- a/drivers/gpu/drm/panthor/panthor_gem.h
> +++ b/drivers/gpu/drm/panthor/panthor_gem.h
> @@ -61,6 +61,11 @@ struct panthor_kernel_bo {
>  	 */
>  	struct drm_gem_object *obj;
>  
> +	/**
> +	 * @vm: VM this private buffer is attached to.
> +	 */
> +	struct panthor_vm *vm;
> +
>  	/**
>  	 * @va_node: VA space allocated to this GEM.
>  	 */
> @@ -136,7 +141,6 @@ panthor_kernel_bo_create(struct panthor_device *ptdev, struct panthor_vm *vm,
>  			 size_t size, u32 bo_flags, u32 vm_map_flags,
>  			 u64 gpu_va);
>  
> -void panthor_kernel_bo_destroy(struct panthor_vm *vm,
> -			       struct panthor_kernel_bo *bo);
> +void panthor_kernel_bo_destroy(struct panthor_kernel_bo *bo);
>  
>  #endif /* __PANTHOR_GEM_H__ */
> diff --git a/drivers/gpu/drm/panthor/panthor_heap.c b/drivers/gpu/drm/panthor/panthor_heap.c
> index 143fa35f2e74..65921296a18c 100644
> --- a/drivers/gpu/drm/panthor/panthor_heap.c
> +++ b/drivers/gpu/drm/panthor/panthor_heap.c
> @@ -127,7 +127,7 @@ static void panthor_free_heap_chunk(struct panthor_vm *vm,
>  	heap->chunk_count--;
>  	mutex_unlock(&heap->lock);
>  
> -	panthor_kernel_bo_destroy(vm, chunk->bo);
> +	panthor_kernel_bo_destroy(chunk->bo);
>  	kfree(chunk);
>  }
>  
> @@ -183,7 +183,7 @@ static int panthor_alloc_heap_chunk(struct panthor_device *ptdev,
>  	return 0;
>  
>  err_destroy_bo:
> -	panthor_kernel_bo_destroy(vm, chunk->bo);
> +	panthor_kernel_bo_destroy(chunk->bo);
>  
>  err_free_chunk:
>  	kfree(chunk);
> @@ -391,7 +391,7 @@ int panthor_heap_return_chunk(struct panthor_heap_pool *pool,
>  	mutex_unlock(&heap->lock);
>  
>  	if (removed) {
> -		panthor_kernel_bo_destroy(pool->vm, chunk->bo);
> +		panthor_kernel_bo_destroy(chunk->bo);
>  		kfree(chunk);
>  		ret = 0;
>  	} else {
> @@ -587,7 +587,7 @@ void panthor_heap_pool_destroy(struct panthor_heap_pool *pool)
>  		drm_WARN_ON(&pool->ptdev->base, panthor_heap_destroy_locked(pool, i));
>  
>  	if (!IS_ERR_OR_NULL(pool->gpu_contexts))
> -		panthor_kernel_bo_destroy(pool->vm, pool->gpu_contexts);
> +		panthor_kernel_bo_destroy(pool->gpu_contexts);
>  
>  	/* Reflects the fact the pool has been destroyed. */
>  	pool->vm = NULL;
> diff --git a/drivers/gpu/drm/panthor/panthor_sched.c b/drivers/gpu/drm/panthor/panthor_sched.c
> index 1d2708c3ab0a..6ea094b00cf9 100644
> --- a/drivers/gpu/drm/panthor/panthor_sched.c
> +++ b/drivers/gpu/drm/panthor/panthor_sched.c
> @@ -826,8 +826,8 @@ static void group_free_queue(struct panthor_group *group, struct panthor_queue *
>  
>  	panthor_queue_put_syncwait_obj(queue);
>  
> -	panthor_kernel_bo_destroy(group->vm, queue->ringbuf);
> -	panthor_kernel_bo_destroy(panthor_fw_vm(group->ptdev), queue->iface.mem);
> +	panthor_kernel_bo_destroy(queue->ringbuf);
> +	panthor_kernel_bo_destroy(queue->iface.mem);
>  
>  	kfree(queue);
>  }
> @@ -837,15 +837,14 @@ static void group_release_work(struct work_struct *work)
>  	struct panthor_group *group = container_of(work,
>  						   struct panthor_group,
>  						   release_work);
> -	struct panthor_device *ptdev = group->ptdev;
>  	u32 i;
>  
>  	for (i = 0; i < group->queue_count; i++)
>  		group_free_queue(group, group->queues[i]);
>  
> -	panthor_kernel_bo_destroy(panthor_fw_vm(ptdev), group->suspend_buf);
> -	panthor_kernel_bo_destroy(panthor_fw_vm(ptdev), group->protm_suspend_buf);
> -	panthor_kernel_bo_destroy(group->vm, group->syncobjs);
> +	panthor_kernel_bo_destroy(group->suspend_buf);
> +	panthor_kernel_bo_destroy(group->protm_suspend_buf);
> +	panthor_kernel_bo_destroy(group->syncobjs);
>  
>  	panthor_vm_put(group->vm);
>  	kfree(group);
> -- 
> 2.44.0
> 

-- 
====================
| I would like to |
| fix the world,  |
| but they're not |
| giving me the   |
 \ source code!  /
  ---------------
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