On Wed, Jan 07, 2026 at 10:47:09PM -0600, Nicholas Sielicki wrote:
>
> +static ssize_t show_modinfo_import_ns(const struct module_attribute *mattr,
> + struct module_kobject *mk, char *buffer)
> +{
> + return sysfs_emit(buffer, "%s\n", mk->mod->imported_namespaces);
> +}
> +
> +static int modinfo_import_ns_exists(struct module *mod)
> +{
> + return mod->imported_namespaces != NULL;
> +}
> +
> +static const struct module_attribute modinfo_import_ns = {
> + .attr = { .name = "import_ns", .mode = 0444 },
> + .show = show_modinfo_import_ns,
> + .test = modinfo_import_ns_exists,
> +};
> +
Don't we need a .setup function that initializes mod->imported_namespaces
to NULL? Currently, if setup_modinfo returns an error, the pointer remains
initialized to whatever value we read from .gnu.linkonce.this_module, and
we'll pass that arbitrary pointer to kfree.
This isn't normally a problem since modpost zero-initializes the field, but
we don't want to rely on userspace to initialize our pointers.
Also, define .free to release the buffer instead of adding a direct call
to free_modinfo.
> static struct {
> char name[MODULE_NAME_LEN];
> char taints[MODULE_FLAGS_BUF_SIZE];
> @@ -1058,6 +1075,7 @@ const struct module_attribute *const modinfo_attrs[] = {
> &module_uevent,
> &modinfo_version,
> &modinfo_srcversion,
> + &modinfo_import_ns,
> &modinfo_initstate,
> &modinfo_coresize,
> #ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
> @@ -1753,11 +1771,48 @@ static void module_license_taint_check(struct module
> *mod, const char *license)
> }
> }
>
> +static int copy_modinfo_import_ns(struct module *mod, struct load_info *info)
> +{
> + char *ns;
> + size_t len, total_len = 0;
> + char *buf, *p;
> +
> + for_each_modinfo_entry(ns, info, "import_ns")
> + total_len += strlen(ns) + 1;
> +
> + if (!total_len) {
> + mod->imported_namespaces = NULL;
> + return 0;
> + }
> +
> + buf = kmalloc(total_len, GFP_KERNEL);
> + if (!buf)
> + return -ENOMEM;
For example, if kmalloc fails, mod->imported_namespaces isn't initialized.
> +
> + p = buf;
> + for_each_modinfo_entry(ns, info, "import_ns") {
> + len = strlen(ns);
> + memcpy(p, ns, len);
> + p += len;
> + *p++ = '\n';
> + }
> + /* Replace trailing newline with null terminator. */
> + *(p - 1) = '\0';
> +
> + mod->imported_namespaces = buf;
> + return 0;
> +}
> +
> +static void free_modinfo_import_ns(struct module *mod)
> +{
> + kfree(mod->imported_namespaces);
mod->imported_namespaces = NULL;
> +}
> +
> static int setup_modinfo(struct module *mod, struct load_info *info)
> {
> const struct module_attribute *attr;
> char *imported_namespace;
> - int i;
> + int i, err;
>
> for (i = 0; (attr = modinfo_attrs[i]); i++) {
> if (attr->setup)
> @@ -1776,6 +1831,10 @@ static int setup_modinfo(struct module *mod, struct
> load_info *info)
> }
> }
Also setup_modinfo can fail before copy_modinfo_import_ns is even
called.
> + err = copy_modinfo_import_ns(mod, info);
> + if (err)
> + return err;
> +
Sami
