From: David Hildenbrand <david@redhat.com>
To: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>,
"Guilherme G. Piccoli" <gpiccoli@canonical.com>,
linux-mm@kvack.org, kernel-hardening@lists.openwall.com,
linux-hardening@vger.kernel.org,
linux-security-module@vger.kernel.org, kernel@gpiccoli.net,
cascardo@canonical.com, Alexander Potapenko <glider@google.com>,
James Morris <jamorris@linux.microsoft.com>,
Kees Cook <keescook@chromium.org>
Subject: Re: [PATCH] mm, hugetlb: Avoid double clearing for hugetlb pages
Date: Fri, 23 Oct 2020 10:23:07 +0200 [thread overview]
Message-ID: <634a44b5-5947-df02-be63-a68f7b317949@redhat.com> (raw)
In-Reply-To: <20201022085557.GK23790@dhcp22.suse.cz>
On 22.10.20 10:55, Michal Hocko wrote:
> On Thu 22-10-20 10:04:50, David Hildenbrand wrote:
> [...]
>>> None of that would address the original point of this thread, the global
>>> init_on_alloc parameter.
>>
>> Yes, but I guess we're past that: whatever leaves the buddy shall be
>> zeroed out. That's the whole point of that security hardening mechanism.
>
> Hugetlb can control its zeroying behavior via mount option (for
> MAP_HUGETLB controled by a command line parameter). If the page fault
> handler can recognize the pre-initialized pages then both init_on* can
Right, looking at init_on_alloc tells you if you have to zero after
alloc or if it's already been done even though you didn't pass GFP_ZERO.
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2020-10-23 8:23 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-19 18:28 [PATCH] mm, hugetlb: Avoid double clearing for hugetlb pages Guilherme G. Piccoli
2020-10-20 8:20 ` Michal Hocko
2020-10-20 13:36 ` David Hildenbrand
2020-10-20 16:55 ` Mike Kravetz
2020-10-20 19:19 ` Guilherme G. Piccoli
2020-10-20 20:07 ` David Hildenbrand
2020-10-20 20:19 ` Guilherme Piccoli
2020-10-21 6:25 ` Michal Hocko
2020-10-20 20:28 ` David Hildenbrand
2020-10-21 6:15 ` Michal Hocko
2020-10-21 9:50 ` David Hildenbrand
2020-10-21 11:31 ` Michal Hocko
2020-10-21 23:32 ` Mike Kravetz
2020-10-22 8:04 ` David Hildenbrand
2020-10-22 8:55 ` Michal Hocko
2020-10-23 8:23 ` David Hildenbrand [this message]
2020-11-05 19:37 ` Guilherme G. Piccoli
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