Re: [PATCH 02/10] userns: Add per user namespace sysctls.

[ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org (Eric W. Biederman)]

"Serge E. Hallyn" <serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org> writes:

> Quoting Eric W. Biederman (ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org):
>> +static bool setup_userns_sysctls(struct user_namespace *ns)
>> +{
>> +#ifdef CONFIG_SYSCTL
>> +	struct ctl_table *tbl;
>> +	setup_sysctl_set(&ns->set, &set_root, set_is_seen);
>> +	tbl = kmemdup(userns_table, sizeof(userns_table), GFP_KERNEL);
>> +	if (tbl) {
>> +		ns->sysctls = __register_sysctl_table(&ns->set, "userns", tbl);
>> +	}
>
> What happens if tbl is null due to oom?  Would it be better to just
> return false in that case here?

ns->sysctls is initialized to NULL and kfree(NULL) is a noop.
So I don't see any problems.

I admit it isn't a usual pattern for error handling.

>> +	if (!ns->sysctls) {
>> +		kfree(tbl);
>> +		retire_sysctl_set(&ns->set);
>> +		return false;
>> +	}
>> +#endif
>> +	return true;
>> +}

Eric