linux-kernel - Re: Fwd: Started to get "memfd_create() without MFD_EXEC nor MFD_NOEXEC

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Date:   Thu, 1 Jun 2023 09:18:47 +0200
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Bagas Sanjaya <bagasdotme@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux Regressions <regressions@...ts.linux.dev>,
        Linux Memory Management List <linux-mm@...ck.org>
Cc:     Jeff Xu <jeffxu@...gle.com>,
        Daniel Verkamp <dverkamp@...omium.org>,
        Kees Cook <keescook@...omium.org>,
        David Herrmann <dh.herrmann@...il.com>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Hugh Dickins <hughd@...gle.com>, Jann Horn <jannh@...gle.com>,
        Jorge Lucangeli Obes <jorgelo@...omium.org>,
        Shuah Khan <skhan@...uxfoundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Stuart Foster <smf-linux@...ginmedia.com>
Subject: Re: Fwd: Started to get "memfd_create() without MFD_EXEC nor
 MFD_NOEXEC_SEAL"

On 6/1/23 04:07, Bagas Sanjaya wrote:
> Hi,
> 
> I notice a regression report on Bugzilla [1]. Quoting from it:
> 
>> Recent kernels seem to generate this:
>> 
>> "memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=3976 'Xorg'"
>> 
>> Is this a kernel problem or something to do with Xorg ?
>> 
>> Seen in Kernels 6.3.4 and 6.4.0-rc4.
>> 
>> Thanks
> 
> See Bugzilla for the full thread and attached logs (dmesg, xorg, bisection
> log).
> 
> Anyway, I'm adding it to regzbot:
> 
> #regzbot introduced: 105ff5339f498a https://bugzilla.kernel.org/show_bug.cgi?id=217508
> #regzbot title: memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL on Xorg

Hm indeed it seems to have introduced 2 new flags and immediately warn if
any process doesn't use them. Maybe it would make sense for some of the
non-default values of vm.memfd_noexec, but it's too early to warn
unconditionally everywhere, no?

> Thanks.
> 
> [1]: https://bugzilla.kernel.org/show_bug.cgi?id=217508
>