linux-kernel - Re: [PATCH 3/7] x86/vm86: Move userspace accesses to do_sys

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Message-ID: <CALCETrU2Xc_mXwv3pYxKx-bmhY7itfUFYejwWq8QMP-nSqP0Lg@mail.gmail.com>
Date:	Thu, 16 Jul 2015 08:42:35 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	Brian Gerst <brgerst@...il.com>
Cc:	X86 ML <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH 3/7] x86/vm86: Move userspace accesses to do_sys_vm86()

On Thu, Jul 16, 2015 at 4:46 AM, Brian Gerst <brgerst@...il.com> wrote:
> Move the userspace accesses down into the common function in
> preparation for the next set of patches.

Nice!

Could you improve the changelog a bit? You're really changing the way
it works (in a good way).


> -       set_flags(regs->pt.flags, VEFLAGS, X86_EFLAGS_VIF | current->thread.v86mask);
> -       tmp = copy_vm86_regs_to_user(&current->thread.vm86_info->regs, regs);
> -       tmp += put_user(current->thread.screen_bitmap, &current->thread.vm86_info->screen_bitmap);
> -       if (tmp) {
> +       set_flags(regs->pt.flags, VEFLAGS, X86_EFLAGS_VIF | tsk->thread.v86mask);
> +       user = tsk->thread.vm86_info;
> +       put_user_try {

I think that put_user_try/put_user_ex requires access_ok.


> +       get_user_try {
> +               unsigned short seg;

This also needs access_ok, I think.

--Andy
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