2017-12-30 21:22:24

by Thomas Gleixner

Subject: [patch 0/3] x86/pti: Fix various fallout

The small series fixes the recent fallout of the x86/pti merge:

- Remove the stale local_flush_tlb() invocations from the CPU hotplug code

- Remove the stale preempt_disable/enable() pair from __native_flush_tlb()

- Fix a bogus free in the write_ldt() error path

Thanks,

tglx

---
include/asm/tlbflush.h | 14 ++++++++------
kernel/ldt.c | 2 +-
kernel/smpboot.c | 9 ---------
3 files changed, 9 insertions(+), 16 deletions(-)

2017-12-30 21:36:00

by Ingo Molnar

Subject: Re: [patch 0/3] x86/pti: Fix various fallout

* Thomas Gleixner <[email protected]> wrote:

> The small series fixes the recent fallout of the x86/pti merge:
>
> - Remove the stale local_flush_tlb() invocations from the CPU hotplug code
>
> - Remove the stale preempt_disable/enable() pair from __native_flush_tlb()
>
> - Fix a bogus free in the write_ldt() error path

Linus, I suspect -rc6 is imminent, and it would be nice to at least have the LDT
error path fix in. I'll send you these fixes tomorrow, but feel free to pick it up
from email if you wanted to release -rc6 today.

Thanks,

Ingo

2017-12-30 22:06:42

by Linus Torvalds

Subject: Re: [patch 0/3] x86/pti: Fix various fallout

On Sat, Dec 30, 2017 at 1:35 PM, Ingo Molnar <[email protected]> wrote:
>
> Linus, I suspect -rc6 is imminent, and it would be nice to at least have the LDT
> error path fix in. I'll send you these fixes tomorrow, but feel free to pick it up
> from email if you wanted to release -rc6 today.

I'll do rc6 tomorrow probably around this time (early afternoon PST).
So I think I should be ok just waiting for your pull request.

Thanks,

Linus

2017-12-31 02:23:29

by Andy Lutomirski

Subject: Re: [patch 0/3] x86/pti: Fix various fallout

> On Dec 30, 2017, at 2:06 PM, Linus Torvalds <[email protected]> wrote:
>
>> On Sat, Dec 30, 2017 at 1:35 PM, Ingo Molnar <[email protected]> wrote:
>>
>> Linus, I suspect -rc6 is imminent, and it would be nice to at least have the LDT
>> error path fix in. I'll send you these fixes tomorrow, but feel free to pick it up
>> from email if you wanted to release -rc6 today.
>
> I'll do rc6 tomorrow probably around this time (early afternoon PST).
> So I think I should be ok just waiting for your pull request.

FWIW, I think this big is at worst just a memory leak. Once an mm has any LDT mapped, mapping a second one can't fail because the entire LDT area is under 512 pages, meaning that nothing needs to be allocated, so there's no opportunity for failure.

So it's an embarrassing bug, but not catastrophic.

>
> Thanks,
>
> Linus