Re: [PATCH bpf-next v8 04/10] bpf: hold module for bpf_struct_ops_map.

[Martin KaFai Lau <martin.lau@xxxxxxxxx>]

On 10/30/23 12:28 PM, thinker.li@xxxxxxxxx wrote:
> @@ -681,9 +697,17 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr)
>   	if (!st_ops_desc)
>   		return ERR_PTR(-ENOTSUPP);
>   
> +	if (st_ops_desc->btf != btf_vmlinux) {
> +		mod = btf_try_get_module(st_ops_desc->btf);
> +		if (!mod)
> +			return ERR_PTR(-EINVAL);
> +	}
> +
>   	vt = st_ops_desc->value_type;
> -	if (attr->value_size != vt->size)
> -		return ERR_PTR(-EINVAL);
> +	if (attr->value_size != vt->size) {
> +		ret = -EINVAL;
> +		goto errout;
> +	}
>   
>   	t = st_ops_desc->type;
>   
> @@ -694,17 +718,17 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr)
>   		(vt->size - sizeof(struct bpf_struct_ops_value));
>   
>   	st_map = bpf_map_area_alloc(st_map_size, NUMA_NO_NODE);
> -	if (!st_map)
> -		return ERR_PTR(-ENOMEM);
> +	if (!st_map) {
> +		ret = -ENOMEM;
> +		goto errout;
> +	}
>   
>   	st_map->st_ops_desc = st_ops_desc;
>   	map = &st_map->map;
>   
>   	ret = bpf_jit_charge_modmem(PAGE_SIZE);
> -	if (ret) {
> -		__bpf_struct_ops_map_free(map);
> -		return ERR_PTR(ret);
> -	}
> +	if (ret)
> +		goto errout_free;
>   
>   	st_map->image = bpf_jit_alloc_exec(PAGE_SIZE);
>   	if (!st_map->image) {
> @@ -713,23 +737,32 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr)
>   		 * here.
>   		 */
>   		bpf_jit_uncharge_modmem(PAGE_SIZE);
> -		__bpf_struct_ops_map_free(map);
> -		return ERR_PTR(-ENOMEM);
> +		ret = -ENOMEM;
> +		goto errout_free;
>   	}
>   	st_map->uvalue = bpf_map_area_alloc(vt->size, NUMA_NO_NODE);
>   	st_map->links =
>   		bpf_map_area_alloc(btf_type_vlen(t) * sizeof(struct bpf_links *),
>   				   NUMA_NO_NODE);
>   	if (!st_map->uvalue || !st_map->links) {
> -		__bpf_struct_ops_map_free(map);
> -		return ERR_PTR(-ENOMEM);
> +		ret = -ENOMEM;
> +		goto errout_free;
>   	}
>   
>   	mutex_init(&st_map->lock);
>   	set_vm_flush_reset_perms(st_map->image);
>   	bpf_map_init_from_attr(map, attr);
>   
> +	module_put(mod);
> +
>   	return map;
> +
> +errout_free:
> +	__bpf_struct_ops_map_free(map);
> +	btf = NULL;		/* has been released */

btf is not defined. I don't think this patch compiles.
Something from a latter patch?

> +errout:
> +	module_put(mod);
> +	return ERR_PTR(ret);
>   }