From: "David Hildenbrand (Arm)" <david@kernel.org>
To: Vernon Yang <vernon2gm@gmail.com>,
akpm@linux-foundation.org, ljs@kernel.org
Cc: nico.pache@linux.dev, ryan.roberts@arm.com, dev.jain@arm.com,
baohua@kernel.org, lance.yang@linux.dev, usama.arif@linux.dev,
zokeefe@google.com, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, stable@vger.kernel.org,
Vernon Yang <yanglincheng@kylinos.cn>
Subject: Re: [PATCH v4 3/3] mm: khugepaged: fix folio is used after folio_put/unlock()
Date: Mon, 7 Sep 2026 14:27:09 +0200 [thread overview]
Message-ID: <674ddd6c-7854-4864-ac7c-df6823d3a37f@kernel.org> (raw)
In-Reply-To: <20260828055926.346744-4-vernon2gm@gmail.com>
On 8/28/26 07:59, Vernon Yang wrote:
> From: Vernon Yang <yanglincheng@kylinos.cn>
>
> On the rollback path, folio_put() has already dropped the last reference
> of new_folio. On the success path, new_folio is already unlocked and can
> be freed concurrently. The trace_mm_khugepaged_collapse_file() is left
> with a dangling folio pointer.
>
> So using the folio_pfn() before dropping the reference, closing
> use-after-free window.
>
> Acked-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
> Fixes: 4c9473e87e75 ("mm/khugepaged: add tracepoint to collapse_file()")
> Cc: stable@vger.kernel.org
> Signed-off-by: Vernon Yang <yanglincheng@kylinos.cn>
> ---
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
--
Cheers,
David
prev parent reply other threads:[~2026-09-07 12:27 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-28 5:59 [PATCH v4 0/3] mm: khugepaged: fix tracepoint UAF Vernon Yang
2026-08-28 5:59 ` [PATCH v4 1/3] mm: khugepaged: fix swap entry value to folio_pfn() Vernon Yang
2026-09-07 12:25 ` David Hildenbrand (Arm)
2026-09-08 1:35 ` Vernon Yang
2026-09-08 7:39 ` David Hildenbrand (Arm)
2026-08-28 5:59 ` [PATCH v4 2/3] mm: khugepaged: fix folio is used after pte_unmap_unlock() Vernon Yang
2026-09-07 12:26 ` David Hildenbrand (Arm)
2026-08-28 5:59 ` [PATCH v4 3/3] mm: khugepaged: fix folio is used after folio_put/unlock() Vernon Yang
2026-09-07 12:27 ` David Hildenbrand (Arm) [this message]
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