Commit 3690f4a8 authored by Thorsten Blum's avatar Thorsten Blum Committed by Petr Pavlu
Browse files

params: Annotate struct module_param_attrs with __counted_by() 



Add the __counted_by compiler attribute to the flexible array member
attrs to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and
CONFIG_FORTIFY_SOURCE.

Increment num before adding a new param_attribute to the attrs array and
adjust the array index accordingly. Increment num immediately after the
first reallocation such that the reallocation for the NULL terminator
only needs to add 1 (instead of 2) to mk->mp->num.

Use struct_size() instead of manually calculating the size for the
reallocation.

Use krealloc_array() for the additional NULL terminator.

Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: default avatarThorsten Blum <thorsten.blum@linux.dev>
Reviewed-by: default avatarLuis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20250213221352.2625-3-thorsten.blum@linux.dev


Signed-off-by: default avatarPetr Pavlu <petr.pavlu@suse.com>
parent f47d2a3f

kernel/params.c

+13 −16
Original line number Diff line number Diff line
@@ -551,7 +551,7 @@ struct module_param_attrs 
{

	unsigned int num;

	struct attribute_group grp;

	struct param_attribute attrs[];

	struct param_attribute attrs[] __counted_by(num);

};



#ifdef CONFIG_SYSFS
@@ -651,35 +651,32 @@ static __modinit int add_sysfs_param(struct module_kobject *mk, 
	}



	/* Enlarge allocations. */

	new_mp = krealloc(mk->mp,

			  sizeof(*mk->mp) +

			  sizeof(mk->mp->attrs[0]) * (mk->mp->num + 1),

	new_mp = krealloc(mk->mp, struct_size(mk->mp, attrs, mk->mp->num + 1),

			  GFP_KERNEL);

	if (!new_mp)

		return -ENOMEM;

	mk->mp = new_mp;

	mk->mp->num++;



	/* Extra pointer for NULL terminator */

	new_attrs = krealloc(mk->mp->grp.attrs,

			     sizeof(mk->mp->grp.attrs[0]) * (mk->mp->num + 2),

			     GFP_KERNEL);

	new_attrs = krealloc_array(mk->mp->grp.attrs, mk->mp->num + 1,

				   sizeof(mk->mp->grp.attrs[0]), GFP_KERNEL);

	if (!new_attrs)

		return -ENOMEM;

	mk->mp->grp.attrs = new_attrs;



	/* Tack new one on the end. */

	memset(&mk->mp->attrs[mk->mp->num], 0, sizeof(mk->mp->attrs[0]));

	sysfs_attr_init(&mk->mp->attrs[mk->mp->num].mattr.attr);

	mk->mp->attrs[mk->mp->num].param = kp;

	mk->mp->attrs[mk->mp->num].mattr.show = param_attr_show;

	memset(&mk->mp->attrs[mk->mp->num - 1], 0, sizeof(mk->mp->attrs[0]));

	sysfs_attr_init(&mk->mp->attrs[mk->mp->num - 1].mattr.attr);

	mk->mp->attrs[mk->mp->num - 1].param = kp;

	mk->mp->attrs[mk->mp->num - 1].mattr.show = param_attr_show;

	/* Do not allow runtime DAC changes to make param writable. */

	if ((kp->perm & (S_IWUSR | S_IWGRP | S_IWOTH)) != 0)

		mk->mp->attrs[mk->mp->num].mattr.store = param_attr_store;

		mk->mp->attrs[mk->mp->num - 1].mattr.store = param_attr_store;

	else

		mk->mp->attrs[mk->mp->num].mattr.store = NULL;

	mk->mp->attrs[mk->mp->num].mattr.attr.name = (char *)name;

	mk->mp->attrs[mk->mp->num].mattr.attr.mode = kp->perm;

	mk->mp->num++;

		mk->mp->attrs[mk->mp->num - 1].mattr.store = NULL;

	mk->mp->attrs[mk->mp->num - 1].mattr.attr.name = (char *)name;

	mk->mp->attrs[mk->mp->num - 1].mattr.attr.mode = kp->perm;



	/* Fix up all the pointers, since krealloc can move us */

	for (i = 0; i < mk->mp->num; i++)