linux-kernel - Re: [PATCH] arch/x86: reset MXCSR to default in kernel_fpu

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 11 Jun 2020 08:38:18 -0600
From:   Shuah Khan <skhan@...uxfoundation.org>
To:     Petteri Aimonen <jpa@....mail.kapsi.fi>
Cc:     Andy Lutomirski <luto@...capital.net>,
        Andy Lutomirski <luto@...nel.org>,
        Borislav Petkov <bp@...en8.de>, Shuah Khan <shuah@...nel.org>,
        Dave Hansen <dave.hansen@...el.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86-ml <x86@...nel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH] arch/x86: reset MXCSR to default in kernel_fpu_begin()

On 6/2/20 11:19 PM, Petteri Aimonen wrote:
> Hi,
> 
>> Is it correct to assume the stuff checked differs from test to test
>> and done in user-space.
>>
>>> undo_evil_state();
>>
>> Is it correct to assume undoing evil differs from test to test
>> and done in user-space, provide it can be done from userspace.
> 
> Yes, currently the test works like:
> 
> do_test_setup();
> read_from_debugfs_file();
> check_results();
> 

You will need a 4th clanup step step of undo_test_setup().

> and the middle step stays the same. But of course in general case there
> could be argument passing etc, even though the test for this issue
> doesn't need them.
> 
> Myself I don't see the problem with just adding a file under debugfs and
> bind to its read.
> 

thanks,
-- Shuah