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From: Suren Baghdasaryan <surenb@google.com>
To: Michal Hocko <mhocko@suse.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Colin Cross <ccross@google.com>,
	Sumit Semwal <sumit.semwal@linaro.org>,
	Dave Hansen <dave.hansen@intel.com>,
	Kees Cook <keescook@chromium.org>,
	Matthew Wilcox <willy@infradead.org>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Johannes Weiner <hannes@cmpxchg.org>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Christian Brauner <brauner@kernel.org>,
	legion@kernel.org, ran.xiaokai@zte.com.cn, sashal@kernel.org,
	Chris Hyser <chris.hyser@oracle.com>,
	Davidlohr Bueso <dave@stgolabs.net>,
	Peter Collingbourne <pcc@google.com>,
	caoxiaofeng@yulong.com, David Hildenbrand <david@redhat.com>,
	Cyrill Gorcunov <gorcunov@gmail.com>,
	linux-mm <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>,
	kernel-team <kernel-team@android.com>,
	syzbot+aa7b3d4b35f9dc46a366@syzkaller.appspotmail.com
Subject: Re: [PATCH v3 1/1] mm: fix use-after-free when anon vma name is used after vma is freed
Date: Tue, 15 Feb 2022 15:02:54 -0800	[thread overview]
Message-ID: <CAJuCfpGG9zwbvfH5UZkt6cG=woeO0RGE7QxjEpXn=gFhiaDdmQ@mail.gmail.com> (raw)
In-Reply-To: <YgwHhTN4P5yyZqBz@dhcp22.suse.cz>

On Tue, Feb 15, 2022 at 12:05 PM Michal Hocko <mhocko@suse.com> wrote:
>
> One thing I was considering is to check agains ref counte overflo (a
> deep process chain with many vmas could grow really high. ref_count
> interface doesn't provide any easy way to check for overflows as far as
> I could see from a quick glance so I gave up there but the logic would
> be really straightforward. We just create a new anon_vma_name with the same
> content and use it when duplicating if the usage grow really
> (arbitrarily) high.

I went over proposed changes. I see a couple small required fixes
(resetting the name to NULL seems to be missing and I think
dup_vma_anon_name needs some tweaking) but overall quite
straight-forward. I'll post a separate patch to do this refactoring.
The original patch is fixing the UAF issue, so I don't want to mix it
with refactoring. Please let me know if you see an issue with
separating it that way.
Thanks,
Suren.


> --
> Michal Hocko
> SUSE Labs

  reply	other threads:[~2022-02-15 23:03 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-11  1:30 [PATCH v3 1/1] mm: fix use-after-free when anon vma name is used after vma is freed Suren Baghdasaryan
2022-02-15 16:00 ` Michal Hocko
2022-02-15 17:36   ` Suren Baghdasaryan
2022-02-15 19:47   ` Michal Hocko
2022-02-15 20:05     ` Michal Hocko
2022-02-15 23:02       ` Suren Baghdasaryan [this message]
2022-02-16  8:06         ` Michal Hocko
2022-02-17 19:54           ` Suren Baghdasaryan
2022-02-22  5:48             ` Suren Baghdasaryan

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