Re: [PATCH v2] kernel/module: Fix mem leak in module_add_modinfo_attrs

[Jessica Yu]

+++ YueHaibing [30/05/19 21:43 +0800]:
> In module_add_modinfo_attrs if sysfs_create_file
> fails, we forget to free allocated modinfo_attrs
> and roll back the sysfs files.
>
> Fixes: 03e88ae1b13d ("[PATCH] fix module sysfs files reference counting")
> Signed-off-by: YueHaibing <yuehaibing@xxxxxxxxxx>
> ---
> v2: free from '--i' instead of 'i--'
> ---
> kernel/module.c | 16 +++++++++++++++-
> 1 file changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/module.c b/kernel/module.c
> index 6e6712b..78e21a7 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -1723,15 +1723,29 @@ static int module_add_modinfo_attrs(struct module *mod)
> 		return -ENOMEM;
>
> 	temp_attr = mod->modinfo_attrs;
> -	for (i = 0; (attr = modinfo_attrs[i]) && !error; i++) {
> +	for (i = 0; (attr = modinfo_attrs[i]); i++) {
> 		if (!attr->test || attr->test(mod)) {
> 			memcpy(temp_attr, attr, sizeof(*temp_attr));
> 			sysfs_attr_init(&temp_attr->attr);
> 			error = sysfs_create_file(&mod->mkobj.kobj,
> 					&temp_attr->attr);
> +			if (error)
> +				goto error_out;
> 			++temp_attr;
> 		}
> 	}
> +
> +	return 0;
> +
> +error_out:
> +	for (; (attr = &mod->modinfo_attrs[i]) && i >= 0; --i) {

The increment step is executed after the body of the loop, so this is
still starting at i instead of i - 1. I think we need:

	for (--i; (attr = &mod->modinfo_attrs[i]) && i >= 0; i--)

Thanks,

Jessica

> +		if (!attr->attr.name)
> +			break;
> +		sysfs_remove_file(&mod->mkobj.kobj, &attr->attr);
> +		if (attr->free)
> +			attr->free(mod);
> +	}
> +	kfree(mod->modinfo_attrs);
> 	return error;
> }
>
> --
> 2.7.4