linux-hardening - Re: [PATCH v2] x86/mm: Refuse W^X violations

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Date:   Thu, 22 Sep 2022 09:38:09 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Dave Hansen <dave.hansen@...el.com>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        linux-hardening@...r.kernel.org, keescook@...omium.org,
        Sean Christopherson <seanjc@...gle.com>
Subject: Re: [PATCH v2] x86/mm: Refuse W^X violations

On 9/22/22 08:00, Dave Hansen wrote:
> On 9/22/22 00:46, Peter Zijlstra wrote:
>> On Wed, Sep 21, 2022 at 08:09:13PM -0700, Guenter Roeck wrote:
>>
>>> Oh well, that "helped" to hide one of the crashes. Here is another one.
>>> This is with PAE enabled and booting through efi32.
>>
>>> [    1.086592]  efi_runtime_update_mappings+0x36/0x42
>>> [    1.086717]  efi_enter_virtual_mode+0x351/0x36e
>>> [    1.086860]  start_kernel+0x57d/0x60f
>>> [    1.086956]  ? set_intr_gate+0x42/0x55
>>> [    1.087079]  i386_start_kernel+0x43/0x45
>>> [    1.087272]  startup_32_smp+0x161/0x164
>>
>> Does this help? Dave; perhaps we should just let i386 be i386 and let it
>> bitrot :/
> 
> How about we just turn off enforcement for now so that the poor i386
> folks can at least boot?  I have the feeling we're going to get bored
> with even the warnings if they persist for too long, though.
> 

Problem with unfixed warnings is that they hide other problems if persistent,
and they result in warnings to be seen just as useless noise.

Case in point: In ChromeOS, we get literally hundreds of thousands of warning
reports each day (most from drm and wireless drivers). Those originate from
upstream code. No one really cares, and none ever get fixed. Please don't add
more if you don't plan to fix them.

Thanks,
Guenter