> On Aug 30, 2018, at 6:36 AM, Thomas Gleixner <t...@linutronix.de> wrote:
>
>> On Wed, 29 Aug 2018, Nadav Amit wrote:
>> at 8:47 AM, Andy Lutomirski <l...@kernel.org> wrote:
>>
>>> In NMI context, we might be in the middle of context switching or in
>>> the middle of switch_mm_irqs_off(). In either case, CR3 might not
>>> match current->mm, which could cause copy_from_user_nmi() and
>>> friends to read the wrong memory.
>>>
>>> Fix it by adding a new nmi_uaccess_okay() helper and checking it in
>>> copy_from_user_nmi() and in __copy_from_user_nmi()'s callers.
>>>
>>> Cc: sta...@vger.kernel.org
>>> Cc: Peter Zijlstra <pet...@infradead.org>
>>> Cc: Nadav Amit <nadav.a...@gmail.com>
>>> Signed-off-by: Andy Lutomirski <l...@kernel.org>
>>> ---
>>>
>>> Nadav, this is intended for your series. Want to add it right
>>> before the use_temporary_mm() stuff?
>>
>> Sure. Thanks! I will apply the following small fix:
>>
>>> +
>>> +#ifdef CONFIG_DEBUG_VM
>>> + WARN_ON_ONCE(!loaded_mm);
>>> +#endif
>>
>> Will be changed to VM_WARN_ON_ONCE() in the two instances.
>
> Unless I'm completely lost, this can just be applied to tip right
> away. It's not depending on anything else.
>
Fine with me. Do you want to do the VM_WARN_ON cleanup yourself or should I
send a v3?
