Re: [PATCH v3 2/2] ARM: mm: protect show_pte() in do_DataAbort() fallback path

[Xie Yuanbin]

On Fri, 26 Jun 2026 13:37:00 +0100, Russell King wrote:
> On Fri, Jun 26, 2026 at 06:16:15PM +0800, Xie Yuanbin wrote:
>> I suggest that waiting for this patch to be merged first:
>> https://lore.kernel.org/20260625122612.43501-1-xieyuanbin1@xxxxxxxxxx
>> which make sure that interrupts are enabled here.
>
> No, it doesn't ensure that.

Oh, I'm sorry my description wasn't clear. It should make sure that
for user unhandled faults, interrupts are enabled here, without
kernel unhandled faults.

> We are not "fixing" show_pte(), which is a diagnostic function when
> things go wrong in the kernel, and is there to *try* to give us
> information to diagnose what happened. It is *not* a function that
> is used routinely in the kernel.

For kernel faults, I fully agree with it. However, for
user faults, I think "fixing" is necessary.
We might be able to construct a user-mode program in some way to
repeatedly trigger unhandled faults -> show_pte(), such as executing bkpt
instruction, or something else, and then the kernel panic, this may be a
security vulnerability.