Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

H. Peter Anvin
2014-04-12T22:25:51Z

On 04/12/2014 02:53 PM, Linus Torvalds wrote:
> On Sat, Apr 12, 2014 at 12:44 PM, H. Peter Anvin <hpa@zytor.com> wrote:
>> Run a 32-bit VM. The 32-bit kernel does this right.
>
> I really don't think that's the answer.
>
> If people really run these 16-bit programs, we need to allow it.
> Clearly it used to work.
>
> Just make the unconditional "don't allow 16-bit segments" be a sysconf entry.
>

Well, is there more than one user, really... that's my question.

But yes, we can make it configurable, but the default should almost
certainly be off.

-hpa