Re: [PATCH 7/7] x86/uaccess: OOPS or warn on a fault with KERNEL_DS and !pagefault_disabled()

[Andy Lutomirski]

On Wed, May 25, 2016 at 8:33 AM, Borislav Petkov <bp@xxxxxxxxx> wrote:
> On Tue, May 24, 2016 at 03:48:44PM -0700, Andy Lutomirski wrote:
>> +     if (unlikely(!is_user_ds && !pagefault_disabled())) {
>> +             if (extra < TASK_SIZE_MAX) {
>> +                     /*
>> +                      * Accessing user address under KERNEL_DS.  This is a
>> +                      * bug and should be fixed, but OOPSing is not helpful
>> +                      * for exploit mitigation.
>> +                      */
>> +                     WARN_ONCE(1, "BUG: uaccess fault at 0x%lx with KERNEL_DS\n",
>
>                         WARN and BUG?
>
> Also, let's have this string and the one below differ for finding out
> where we are during debugging.

Done.