From: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
To: "Liam R. Howlett" <Liam.Howlett@oracle.com>,
Harry Yoo <harry.yoo@oracle.com>,
Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>, Jann Horn <jannh@google.com>,
Pedro Falcato <pfalcato@suse.de>,
Yeoreum Yun <yeoreum.yun@arm.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
David Hildenbrand <david@kernel.org>,
Jeongjun Park <aha310510@gmail.com>,
Rik van Riel <riel@surriel.com>
Subject: Re: [PATCH] mm/vma: fix anon_vma UAF on mremap() faulted, unfaulted merge
Date: Mon, 5 Jan 2026 15:32:17 +0000 [thread overview]
Message-ID: <b5ffe4ad-690d-4668-97c2-9b94fc1da32b@lucifer.local> (raw)
In-Reply-To: <qhhhf2s2vaajvr3u7k6r3vjbpx6r4ama46kwrt5xsusdoccsi2@ldazcd63kqbb>
On Mon, Jan 05, 2026 at 10:24:13AM -0500, Liam R. Howlett wrote:
> > mremap()
> > |-----------------------------------|
> > | |
> > v |
> > [ VMA C, unfaulted ][ gap ][ VMA B, unfaulted ][ gap ][ VMA A, faulted ]
>
> The key part here is that target == prev in this case (as stated in the
> email linked). So we're going to dup nothing, but we really need to dup
> VMA A's anon vma - right?
Yup.
There are a number other cases like this, mremap() of anon breaks things,
because the copy_vma() case violates sensible assumptions, in the way anon
mremap() violates many other sensible assumptions.
I have a generalised fix I'm just finishing up the tests for it now.
You'll see exactly which cases in the v2 which I'll send later today.
I also noticed another issue which I'll fix in the same series...
Happy New Year! ;)
prev parent reply other threads:[~2026-01-05 15:32 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-02 20:55 Lorenzo Stoakes
2026-01-02 21:00 ` Lorenzo Stoakes
2026-01-04 19:25 ` David Hildenbrand (Red Hat)
2026-01-05 12:53 ` Lorenzo Stoakes
2026-01-05 5:11 ` Harry Yoo
2026-01-05 9:12 ` Lorenzo Stoakes
2026-01-05 15:24 ` Liam R. Howlett
2026-01-05 15:32 ` Lorenzo Stoakes [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=b5ffe4ad-690d-4668-97c2-9b94fc1da32b@lucifer.local \
--to=lorenzo.stoakes@oracle.com \
--cc=Liam.Howlett@oracle.com \
--cc=aha310510@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=david@kernel.org \
--cc=harry.yoo@oracle.com \
--cc=jannh@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=pfalcato@suse.de \
--cc=riel@surriel.com \
--cc=vbabka@suse.cz \
--cc=yeoreum.yun@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox