Re: [PATCH v4] x86/fsgsbase/64: Fix the base write helper functions

[Bae, Chang Seok]

> On Nov 14, 2018, at 13:46, Bae, Chang Seok <chang.seok.bae@xxxxxxxxx> wrote:
> 
> int copy_thread_tls(unsigned long clone_flags, unsigned long sp,
> @@ -758,11 +720,45 @@ long do_arch_prctl_64(struct task_struct *task, int option, unsigned long arg2)
> 
> 	switch (option) {
> 	case ARCH_SET_GS: {
> -		ret = x86_gsbase_write_task(task, arg2);
> +		preempt_disable();
> +		if (unlikely(arg2 >= TASK_SIZE_MAX))
> +			return -EPERM;

Sorry, preempt_disabled() should go after this.
Chang