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params: Annotate struct module_param_attrs with __counted_by()

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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: Thorsten Blum <thorsten.blum@linux.dev>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20250213221352.2625-3-thorsten.blum@linux.dev
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
This commit is contained in:
Thorsten Blum 2025-02-13 23:13:52 +01:00 committed by Petr Pavlu
parent f47d2a3f75
commit 3690f4a860
1 changed files with 13 additions and 16 deletions
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29
kernel/params.c
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@ -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++)