Re: [PATCH v11 32/65] dyndbg: Harden classmap and callsite validation

[Louis Chauvet]

On Fri, 13 Mar 2026 07:19:57 -0600, Jim Cromie <jim.cromie@xxxxxxxxx> wrote:
> diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
> index 0d1245aefc69..28684cfc0937 100644
> --- a/include/linux/dynamic_debug.h
> +++ b/include/linux/dynamic_debug.h
> @@ -262,6 +262,8 @@ struct _ddebug_class_param {
>  
>  #define __DYNAMIC_DEBUG_CLASSMAP_USE(_var, _offset, _uname)		\
>  	extern struct _ddebug_class_map _var;				\
> +	static_assert((_offset) >= 0 && (_offset) < _DPRINTK_CLASS_DFLT, \
> +		      "classmap use offset must be in 0..62");		\

Can't you also check the offset+base?

>
> diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
> index 2083a8546460..635df6edb4cf 100644
> --- a/lib/dynamic_debug.c
> +++ b/lib/dynamic_debug.c
> @@ -1404,9 +1404,8 @@ static void ddebug_apply_class_users(const struct _ddebug_info *di)
>  	(__dst)->info._vec.len = __nc;					\
>  })
>  
> -static int __maybe_unused
> -ddebug_class_range_overlap(struct _ddebug_class_map *cm,
> -			   u64 *reserved_ids)
> +static int ddebug_class_range_overlap(struct _ddebug_class_map *cm,
> +				      u64 *reserved_ids)

I think you can remove the __maybe_unused earlier in the series (23/65
seems to use it).

> @@ -1454,10 +1471,33 @@ static int ddebug_add_module(struct _ddebug_info *di)
> [ ... skip 5 lines ... ]
> +	/* validate class map types and the per-module 0..62 class_id space */
> +	for_subvec(i, cm, &dt->info, maps) {
> +		if (cm->map_type > DD_CLASS_TYPE_LEVEL_NUM) {
> +			pr_err("module %s has unknown classmap type %d\n", dt->info.mod_name, cm->map_type);
> +			goto cleanup;
> +		}

I think this check could be inserted earlier.

-- 
Louis Chauvet <louis.chauvet@xxxxxxxxxxx>